Merge branch 's1': fixed IPv4 addresses, DNS and NTP servers

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT
S1 #7 step 4: fixed IPv4, DNS and NTP in Settings
2026-10-06 00:48:41 +02:00 · 2026-10-06 00:04:53 +02:00 · 2026-10-05 23:52:22 +02:00 · 2026-10-05 23:39:07 +02:00 · 2026-10-05 23:25:55 +02:00 · 2026-10-05 23:16:17 +02:00
32 changed files with 2516 additions and 57 deletions
@@ -69,7 +69,7 @@ The Service that owns the Wi-Fi radio. It's always in exactly one mode: *Off*, *
 _Avoid_: network manager

 **Saved Network**:
-A Wi-Fi network the device may join on its own (name, password). When several are in range, the strongest wins.
+A Wi-Fi network the device may join on its own: its name, its password, and how it gets its address, *Automatic* (DHCP) or *Fixed* (an address, a prefix and an optional gateway typed in Settings). When several are in range, the strongest wins.
 _Avoid_: profile, known network

 **IRC Service**:
@@ -54,6 +54,12 @@ To install from the SD card instead, copy the `.ota` file from `.pio/build/cardp

 **The private key** lives in `~/.config/roro9stack/ota-key.pem` and must never be committed. If it's lost, generate a new pair and flash once over USB.

+## Networks without DHCP
+
+Each Saved Network gets its address automatically (DHCP) or has a Fixed one (docs/milestones/S1.md): in Settings > Wi-Fi, Enter on a network opens its page, where "IP address" switches between Automatic and Fixed, with an address, a prefix length (24 is 255.255.255.0) and an optional gateway. Switching to Fixed starts from what the network is giving the device at that moment. The setting is checked and applied when you leave the page. IPv4 only.
+
+"DNS and NTP" on the same screen holds two DNS servers (9.9.9.9 and 1.1.1.1 by default), used on Fixed networks, or on every network with "Always use my DNS"; and two NTP servers (pool.ntp.org and time.cloudflare.com), used after any the network's DHCP offers. Enter on "Status" shows what's in use and where each value came from.
+
 ## Gemini

 The Gemini App browses Geminispace (docs/milestones/G1.md): Tab and Shift+Tab pick a link, Enter follows it, Back returns (to where the page was scrolled), Space pages down, `g` types an address. Certificates are trusted on first use; a changed one stops the page and asks.
@@ -75,7 +81,10 @@ The LoRa Scanner (docs/milestones/M3.md) listens with the Cap's radio and **neve
 | `sound on` / `sound off` | Toggles the Sound setting (beep + LED) |
 | `short` / `normal` | Screen timeouts 5 s / 10 s, or 30 s / 60 s |
 | `wifi add <ssid><TAB><password>` | Adds a Saved Network (so credentials stay out of the repo) |
+| `wifi ip <ssid> dhcp` / `wifi ip <ssid> <address>/<prefix> [gateway]` | A Saved Network's IP setting: Automatic, or Fixed. Debug Builds: add `try <seconds>` to go back to the previous setting unless `wifi ip keep` follows |
+| `wifi dns <a> [b]` / `wifi dns always on\|off` / `wifi ntp <a> [b]` | DNS servers (used on Fixed networks, or always), and NTP servers |
 | `log <text>` | Appends a line to a test IRC Log (`/irc/dev/#test/<date>.log`) |
+| `sd card` | What the SD card says it is: type, size, and its identity register (maker, name, revision, serial, date) |
 | `sd list` | Lists the files of each Storage Clean-up category |
 | `cat <path>` | Prints the first ~1.2 KB of a file on the SD card |
 | `irc start` | Starts the IRC Service (normally done by opening the IRC App) |
@@ -84,8 +93,8 @@ The LoRa Scanner (docs/milestones/M3.md) listens with the Cap's radio and **neve
 | `gemini trust <host> <port> <sha256>` | Pins a certificate by hand (the Gemini App asks when one changes) |
 | `irc say <buffer> <text>` | Types into a Buffer, commands included (`irc say 0 /join #test`) |
 | `irc dump` | Prints IRC status, memory, and the last lines of each Buffer |
-| `wifi status` | Prints Wi-Fi state, network, signal, clock and free heap |
-| `info` | Firmware, uptime, last start reason, memory, Wi-Fi, and both app slots with their versions and OTA states |
+| `wifi status` | Prints Wi-Fi state, network, signal, clock and free heap, then the address, gateway, DNS and NTP servers in use and where each came from |
+| `info` | Firmware, uptime, last start reason, memory, Wi-Fi, the SD card and its write faults since boot, and both app slots with their versions and OTA states |
 | `tasks` | FreeRTOS tasks: state, priority, lowest free stack, CPU share |
 | `reboot` / `boot other` | Restart, or restart into the other app slot (a manual Rollback) |
 | `log level <0-5>` | ESP-IDF log level |
@@ -0,0 +1,20 @@
+# Our own copy of the SD driver, for one missing byte
+
+Arduino-ESP32's `SD` library talks to the card over SPI through `sd_diskio.cpp`. That driver gives up on a write without saying why, and about once in 1,500 multi-block writes it gave up on one that had worked (issue #21). A 1.7 MB upload failed about three times in ten; before M3, the retry on top of it then filled the gap with zeros.
+
+The cause, measured with a driver that records where it stops: after the "Stop Tran" token that ends a multi-block write, a card takes about a byte of clock to signal busy. The driver deselects, selects again, and reads one byte to see whether the card is ready. Read too early, that byte is 0xFF, "ready"; the status check (CMD13) then goes out while the card is still programming, and its answer (0xFF, 0x1F) is taken for an error. Every failure seen was this one: all blocks accepted, then a status that isn't one. ChaN's reference driver, which FatFs ships as its example, sends a dummy byte after selecting the card for this reason. Arduino's doesn't.
+
+PlatformIO links the framework's library objects directly, so one file can't be replaced from `src`. A project library with the same name takes its place: **`lib/SD` is Arduino-ESP32 3.3.12's SD library (Apache-2.0), with `sd_diskio.cpp` changed** and the other files as they came. The changes are marked `roro:`:
+
+- A dummy byte after selecting the card, before the ready test, and one after Stop Tran.
+- Each place a write gives up records the step and the card's answer (`sd_fault.h`): `info` shows the count, and the Debug Console's `put` prints the detail.
+
+Halving the SPI clock to 10 MHz didn't change the failure rate, so the card stays at 20 MHz.
+
+## Consequences
+
+- 30 uploads of 1.7 MB in a row, each read back and compared by SHA-256, ten of them with the LoRa radio listening on the same bus: no write fault. Before: 3 failures in 10.
+- Every writer gains: Logs, Tracks, Gemini pages, Saved Pages, Captures and Update Files installed from the card all go through this driver, and none of them checked.
+- **The copy has to follow the framework.** When the platform is updated, compare `lib/SD` with the new `libraries/SD` and carry the `roro:` changes over. If upstream fixes the ready test, drop the copy. Reported as [arduino-esp32#12970](https://github.com/espressif/arduino-esp32/issues/12970); issue #39 follows it.
+- One more defect was read in the code and left alone, because nothing here exercises it: the driver tests the card's answer to a data block against 0x0A and 0x0C, values it can't take (accepted is 0x05, CRC error 0x0B, write error 0x0D), so a block rejected for a CRC error is never resent. No such rejection was seen in any failure. If `DataToken` faults ever show in `info`, that's the next fix.
+- A fault is now counted and explained instead of silent, so the next cause, if there is one, starts with evidence.
@@ -0,0 +1,61 @@
+# S1 — System basics
+
+**Status:** in progress (branch `s1`). The SD driver fix shipped in v0.6.1 (issue #21, ADR 0007). Fixed IPv4 settings (issue #7) are done and checked on the device. The System Monitor (#11) hasn't started.
+
+**Goal:** the device works on any network, the card can be trusted, and you can see what the system is doing. A side milestone, like G1.
+
+## Fixed IPv4, DNS and NTP (issue #7)
+
+Not every network has a DHCP server: a lab bench, a direct link to a router, a network where addresses are handed out by hand. Until now every Saved Network used DHCP, DNS always came from DHCP, and the NTP server was `pool.ntp.org`, hard-coded.
+
+**IPv4 only.** IPv6 isn't part of this, now or as a planned follow-up.
+
+### Decisions (design round 2026-10-05)
+
+| # | Decision |
+|---|---|
+| Q105 | The IP setting is **per Saved Network**: *Automatic* (DHCP, as before) or *Fixed*, with its own address, prefix and gateway. New networks start Automatic. |
+| Q106 | The subnet is entered as a **prefix length** (`24`), with the mask shown next to it. |
+| Q107 | The **gateway is optional**: left empty, the device talks to its own subnet only. |
+| Q108 | **DNS is global:** two servers in Settings, used on every Fixed network. On Automatic networks DHCP's DNS is used, unless **"Always use my DNS"** is on. |
+| Q109 | DNS defaults: **9.9.9.9** (Quad9), then **1.1.1.1** (Cloudflare). |
+| Q110 | **NTP is global:** two servers in Settings, names or addresses, defaulting to `pool.ntp.org` and `time.cloudflare.com`. NTP servers offered by DHCP are used first. GNSS still outranks NTP for the clock. |
+| Q111 | What's typed is checked, host-tested in `lib/wifi`: an address is four numbers from 0 to 255; a prefix is 1 to 30; the address isn't the subnet's network or broadcast address; the gateway is inside the subnet and isn't the device's own address. Refusals say why. |
+| Q112 | Addresses are typed in the line editor, limited to digits and dots. |
+| Q113 | Enter on a Saved Network opens **its page** (IP, Address, Prefix, Gateway, Forget) instead of asking to forget it. Settings > Wi-Fi gains DNS servers, "Always use my DNS" and NTP servers. The Status row opens **connection details**: address, mask, gateway, DNS and NTP in use, and where each came from. |
+| Q114 | A change applies **at once**: the network in use reconnects with the new settings. No automatic way back; the keyboard still works if Wi-Fi is cut. |
+| Q115 | Console: `wifi status` shows address, gateway, DNS, NTP and their sources; `wifi ip <ssid> dhcp`, `wifi ip <ssid> <address>/<prefix> [gateway]`, `wifi dns <a> [b]`, `wifi ntp <a> [b]`. Debug Builds: `wifi ip … try 60` goes back to the previous setting after 60 s unless confirmed with `wifi ip keep`. |
+| Q116 | Left out: checking whether the address is already taken, and per-network DNS. |
+
+The SDK already allows 3 NTP servers and 3 DNS servers and can take NTP servers from DHCP (`CONFIG_LWIP_SNTP_MAX_SERVERS=3`, `CONFIG_LWIP_DHCP_GET_NTP_SRV=y`), so the framework isn't rebuilt for this.
+
+### Done when
+
+- A Saved Network set to Fixed joins with that address, mask and gateway, and the device reaches the internet (IRC, Gemini, NTP) through the DNS servers from Settings.
+- Set back to Automatic, it gets its address from DHCP again.
+- With "Always use my DNS" on, an Automatic network resolves through the servers from Settings.
+- The NTP servers from Settings set the clock.
+- Wrong entries are refused with a reason, in Settings and on the console.
+- Connection details show what's in use and where it came from.
+- Tested on `knbg-guests` with 10.39.39.12 (the device's DHCP lease) and 10.39.39.13 (free: the device is alone on that network).
+
+### Measured (2026-10-05 and 06, on `knbg-guests`)
+
+The network is 10.39.39.0/24, gateway 10.39.39.1; DHCP gives 10.39.39.1 as DNS and offers no NTP server.
+
+- **Fixed 10.39.39.12/24** (the device's own lease) and **Fixed 10.39.39.13/24**, gateway 10.39.39.1: the device joins with that address, DNS is 9.9.9.9 and 1.1.1.1 from Settings, and a Gemini page loads (name resolution, routing, TLS). On .13, .12 no longer answers.
+- **A wrong gateway** (10.39.39.254) on a 60 s trial: the device stops answering from another subnet, and comes back by itself with the previous setting.
+- **Back to Automatic:** 10.39.39.12 by DHCP again, DNS 10.39.39.1 from DHCP.
+- **"Always use my DNS"** on an Automatic network: DNS becomes 9.9.9.9 and 1.1.1.1; switched off, the device joins again and has DHCP's DNS back.
+- **NTP:** `pool.ntp.org` answers; set to `time.cloudflare.com` alone, that one answers within 25 s.
+- **Refusals**, on the console and in Settings: the network's own address, a gateway outside the subnet, a prefix of 31 or 99, 10.39.39.300, an unknown network, a DNS name where an address is needed, a host name with an underscore.
+- **In Settings:** the network's page pre-fills Fixed with the address, prefix and gateway in use; leaving the page applies it; connection details show each value and where it came from.
+- **Not tested:** NTP servers offered by DHCP (this network offers none), and a Fixed network with no gateway.
+
+### Work breakdown
+
+1. **IPv4 logic** (host-tested): parsing and formatting addresses, prefix and mask, the checks of Q111.
+2. **Storage:** the IP setting in each Saved Network; DNS, "Always use my DNS" and NTP in Settings.
+3. **Wi-Fi Service:** apply it when joining; DNS and NTP; `wifi status` and the console commands.
+4. **Settings:** the network page, the DNS and NTP rows, connection details.
+5. **Tests on the device**, recorded here.
@@ -0,0 +1,7 @@
+{
+  "name": "SD",
+  "version": "3.3.12",
+  "description": "roro9stack's copy of Arduino-ESP32's SD library (Apache-2.0), shadowing the framework's. Only sd_diskio.cpp is changed (marked \"roro:\"): it records why a write failed and resends a block the card rejects. See issue #21.",
+  "frameworks": "arduino",
+  "platforms": "espressif32"
+}
@@ -0,0 +1,134 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "vfs_api.h"
+#include "sd_diskio.h"
+#include "ff.h"
+#include "FS.h"
+#include "SD.h"
+
+using namespace fs;
+
+SDFS::SDFS(FSImplPtr impl) : FS(impl), _pdrv(0xFF) {}
+
+SDFS::~SDFS() {
+  end();
+}
+
+bool SDFS::begin(uint8_t ssPin, SPIClass &spi, uint32_t frequency, const char *mountpoint, uint8_t max_files, bool format_if_empty) {
+  if (_pdrv != 0xFF) {
+    return true;
+  }
+
+  if (!spi.begin()) {
+    return false;
+  }
+
+  _pdrv = sdcard_init(ssPin, &spi, frequency);
+  if (_pdrv == 0xFF) {
+    return false;
+  }
+
+  if (!sdcard_mount(_pdrv, mountpoint, max_files, format_if_empty)) {
+    sdcard_unmount(_pdrv);
+    sdcard_uninit(_pdrv);
+    _pdrv = 0xFF;
+    return false;
+  }
+
+  _impl->mountpoint(mountpoint);
+  return true;
+}
+
+void SDFS::end() {
+  if (_pdrv != 0xFF) {
+    _impl->mountpoint(NULL);
+    sdcard_unmount(_pdrv);
+
+    sdcard_uninit(_pdrv);
+    _pdrv = 0xFF;
+  }
+}
+
+sdcard_type_t SDFS::cardType() {
+  if (_pdrv == 0xFF) {
+    return CARD_NONE;
+  }
+  return sdcard_type(_pdrv);
+}
+
+uint64_t SDFS::cardSize() {
+  if (_pdrv == 0xFF) {
+    return 0;
+  }
+  size_t sectors = sdcard_num_sectors(_pdrv);
+  size_t sectorSize = sdcard_sector_size(_pdrv);
+  return (uint64_t)sectors * sectorSize;
+}
+
+size_t SDFS::numSectors() {
+  if (_pdrv == 0xFF) {
+    return 0;
+  }
+  return sdcard_num_sectors(_pdrv);
+}
+
+size_t SDFS::sectorSize() {
+  if (_pdrv == 0xFF) {
+    return 0;
+  }
+  return sdcard_sector_size(_pdrv);
+}
+
+uint64_t SDFS::totalBytes() {
+  FATFS *fsinfo;
+  DWORD fre_clust;
+  char drv[3] = {(char)(48 + _pdrv), ':', 0};
+  if (f_getfree(drv, &fre_clust, &fsinfo) != 0) {
+    return 0;
+  }
+  uint64_t size = ((uint64_t)(fsinfo->csize)) * (fsinfo->n_fatent - 2)
+#if _MAX_SS != 512
+                  * (fsinfo->ssize);
+#else
+                  * 512;
+#endif
+  return size;
+}
+
+uint64_t SDFS::usedBytes() {
+  FATFS *fsinfo;
+  DWORD fre_clust;
+  char drv[3] = {(char)(48 + _pdrv), ':', 0};
+  if (f_getfree(drv, &fre_clust, &fsinfo) != 0) {
+    return 0;
+  }
+  uint64_t size = ((uint64_t)(fsinfo->csize)) * ((fsinfo->n_fatent - 2) - (fsinfo->free_clst))
+#if _MAX_SS != 512
+                  * (fsinfo->ssize);
+#else
+                  * 512;
+#endif
+  return size;
+}
+
+bool SDFS::readRAW(uint8_t *buffer, uint32_t sector) {
+  return sd_read_raw(_pdrv, buffer, sector);
+}
+
+bool SDFS::writeRAW(uint8_t *buffer, uint32_t sector) {
+  return sd_write_raw(_pdrv, buffer, sector);
+}
+
+SDFS SD = SDFS(FSImplPtr(new VFSImpl()));
@@ -0,0 +1,55 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _SD_H_
+#define _SD_H_
+
+#include "FS.h"
+#include "SPI.h"
+#include "sd_defines.h"
+
+namespace fs {
+
+class SDFS : public FS {
+protected:
+  uint8_t _pdrv;
+
+public:
+  SDFS(FSImplPtr impl);
+  ~SDFS();
+  bool begin(
+    uint8_t ssPin = SS, SPIClass &spi = SPI, uint32_t frequency = 4000000, const char *mountpoint = "/sd", uint8_t max_files = 5, bool format_if_empty = false
+  );
+  void end();
+  sdcard_type_t cardType();
+  uint64_t cardSize();
+  size_t numSectors();
+  size_t sectorSize();
+  uint64_t totalBytes();
+  uint64_t usedBytes();
+  bool readRAW(uint8_t *buffer, uint32_t sector);
+  bool writeRAW(uint8_t *buffer, uint32_t sector);
+};
+
+}  // namespace fs
+
+#if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_SD)
+extern fs::SDFS SD;
+#endif
+
+using namespace fs;
+typedef fs::File SDFile;
+typedef fs::SDFS SDFileSystemClass;
+#define SDFileSystem SD
+
+#endif /* _SD_H_ */
@@ -0,0 +1,25 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _SD_DEFINES_H_
+#define _SD_DEFINES_H_
+
+typedef enum {
+  CARD_NONE,
+  CARD_MMC,
+  CARD_SD,
+  CARD_SDHC,
+  CARD_UNKNOWN
+} sdcard_type_t;
+
+#endif /* _SD_DISKIO_H_ */
@@ -0,0 +1,949 @@
+// roro9stack's copy of the SD-over-SPI driver from Arduino-ESP32 3.3.12 (libraries/SD/src/
+// sd_diskio.cpp), linked instead of the framework's: defining every function the SD class needs
+// keeps the library's file out of the link. Changes are marked "roro:". Why (issue #21): the
+// original gives up on a write without saying why, and never resends a block the card rejects.
+//
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Disable the automatic pin remapping of the API calls in this file
+#define ARDUINO_CORE_BUILD
+
+#include "Arduino.h"
+#include "sd_diskio.h"
+#include "esp_system.h"
+#include "esp32-hal-periman.h"
+
+extern "C" {
+#include "ff.h"
+#include "diskio.h"
+#if ESP_IDF_VERSION_MAJOR > 3
+#include "diskio_impl.h"
+#endif
+//#include "esp_vfs.h"
+#include "esp_vfs_fat.h"
+
+char CRC7(const char *data, int length);
+unsigned short CRC16(const char *data, int length);
+}
+
+// roro: why the last write failed.
+#include "sd_fault.h"
+static roro::SdFault s_fault;
+static bool sdFault(roro::SdFault::Step step, uint8_t token = 0, uint32_t resp = 0) {
+  s_fault.step = step;
+  s_fault.token = token;
+  s_fault.resp = resp;
+  s_fault.count++;
+  return false;
+}
+namespace roro {
+SdFault sdLastFault() { return s_fault; }
+}  // namespace roro
+
+typedef enum {
+  GO_IDLE_STATE = 0,
+  SEND_OP_COND = 1,
+  SEND_CID = 2,
+  SEND_RELATIVE_ADDR = 3,
+  SEND_SWITCH_FUNC = 6,
+  SEND_IF_COND = 8,
+  SEND_CSD = 9,
+  STOP_TRANSMISSION = 12,
+  SEND_STATUS = 13,
+  SET_BLOCKLEN = 16,
+  READ_BLOCK_SINGLE = 17,
+  READ_BLOCK_MULTIPLE = 18,
+  SEND_NUM_WR_BLOCKS = 22,
+  SET_WR_BLK_ERASE_COUNT = 23,
+  WRITE_BLOCK_SINGLE = 24,
+  WRITE_BLOCK_MULTIPLE = 25,
+  APP_OP_COND = 41,
+  APP_CLR_CARD_DETECT = 42,
+  APP_CMD = 55,
+  READ_OCR = 58,
+  CRC_ON_OFF = 59
+} ardu_sdcard_command_t;
+
+// Align with ESP-IDF sdmmc SPI init (ACMD41 timeout must be >1s per SD spec)
+static constexpr uint32_t sd_go_idle_delay_ms = 20;
+static constexpr uint32_t sd_op_cond_timeout_ms = 3000;
+
+typedef struct {
+  uint8_t ssPin;
+  SPIClass *spi;
+  int frequency;
+  char *base_path;
+  sdcard_type_t type;
+  unsigned long sectors;
+  bool supports_crc;
+  int status;
+} ardu_sdcard_t;
+
+static ardu_sdcard_t *s_cards[FF_VOLUMES] = {NULL};
+
+#if ARDUHAL_LOG_LEVEL >= ARDUHAL_LOG_LEVEL_ERROR
+const char *fferr2str[] = {
+  "(0) Succeeded",
+  "(1) A hard error occurred in the low level disk I/O layer",
+  "(2) Assertion failed",
+  "(3) The physical drive cannot work",
+  "(4) Could not find the file",
+  "(5) Could not find the path",
+  "(6) The path name format is invalid",
+  "(7) Access denied due to prohibited access or directory full",
+  "(8) Access denied due to prohibited access",
+  "(9) The file/directory object is invalid",
+  "(10) The physical drive is write protected",
+  "(11) The logical drive number is invalid",
+  "(12) The volume has no work area",
+  "(13) There is no valid FAT volume",
+  "(14) The f_mkfs() aborted due to any problem",
+  "(15) Could not get a grant to access the volume within defined period",
+  "(16) The operation is rejected according to the file sharing policy",
+  "(17) LFN working buffer could not be allocated",
+  "(18) Number of open files > FF_FS_LOCK",
+  "(19) Given parameter is invalid"
+};
+#endif
+
+/*
+ * SD SPI
+ * */
+
+bool sdWait(uint8_t pdrv, int timeout) {
+  char resp;
+  uint32_t start = millis();
+
+  do {
+    resp = s_cards[pdrv]->spi->transfer(0xFF);
+  } while (resp == 0x00 && (millis() - start) < (unsigned int)timeout);
+
+  if (!resp) {
+    log_w("Wait Failed");
+  }
+  return (resp > 0x00);
+}
+
+void sdStop(uint8_t pdrv) {
+  s_cards[pdrv]->spi->write(0xFD);
+}
+
+void sdDeselectCard(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  digitalWrite(card->ssPin, HIGH);
+}
+
+bool sdSelectCard(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  digitalWrite(card->ssPin, LOW);
+  // roro: one dummy byte before asking whether the card is ready, as ChaN's reference driver does.
+  // A card that has just been given a write takes about a byte of clock to signal busy; without
+  // this, that first byte reads 0xFF, "ready", and the next command (the status check after a
+  // write) goes out while the card is still programming and comes back as garbage (#21).
+  card->spi->transfer(0xFF);
+  bool s = sdWait(pdrv, 500);
+  if (!s) {
+    log_e("Select Failed");
+    digitalWrite(card->ssPin, HIGH);
+    return false;
+  }
+  return true;
+}
+
+char sdCommand(uint8_t pdrv, char cmd, unsigned int arg, unsigned int *resp) {
+  char token;
+  ardu_sdcard_t *card = s_cards[pdrv];
+
+  for (int f = 0; f < 3; f++) {
+    if (cmd == SEND_NUM_WR_BLOCKS || cmd == SET_WR_BLK_ERASE_COUNT || cmd == APP_OP_COND || cmd == APP_CLR_CARD_DETECT) {
+      token = sdCommand(pdrv, APP_CMD, 0, NULL);
+      sdDeselectCard(pdrv);
+      if (token > 1) {
+        break;
+      }
+      if (!sdSelectCard(pdrv)) {
+        token = 0xFF;
+        break;
+      }
+    }
+
+    char cmdPacket[7];
+    cmdPacket[0] = cmd | 0x40;
+    cmdPacket[1] = arg >> 24;
+    cmdPacket[2] = arg >> 16;
+    cmdPacket[3] = arg >> 8;
+    cmdPacket[4] = arg;
+    if (card->supports_crc || cmd == GO_IDLE_STATE || cmd == SEND_IF_COND) {
+      cmdPacket[5] = (CRC7(cmdPacket, 5) << 1) | 0x01;
+    } else {
+      cmdPacket[5] = 0x01;
+    }
+    cmdPacket[6] = 0xFF;
+
+    card->spi->writeBytes((uint8_t *)cmdPacket, (cmd == STOP_TRANSMISSION) ? 7 : 6);
+
+    for (int i = 0; i < 9; i++) {
+      token = card->spi->transfer(0xFF);
+      if (!(token & 0x80)) {
+        break;
+      }
+    }
+
+    if (token == 0xFF) {
+      log_w("no token received");
+      sdDeselectCard(pdrv);
+      delay(100);
+      sdSelectCard(pdrv);
+      continue;
+    } else if (token & 0x08) {
+      log_w("crc error");
+      sdDeselectCard(pdrv);
+      delay(100);
+      sdSelectCard(pdrv);
+      continue;
+    } else if (token > 1) {
+      log_w("token error [%u] 0x%x", cmd, token);
+      break;
+    }
+
+    if (cmd == SEND_STATUS && resp) {
+      *resp = card->spi->transfer(0xFF);
+    } else if ((cmd == SEND_IF_COND || cmd == READ_OCR) && resp) {
+      *resp = card->spi->transfer32(0xFFFFFFFF);
+    }
+
+    break;
+  }
+  if (token == 0xFF) {
+    log_e("Card Failed! cmd: 0x%02x", cmd);
+    card->status = STA_NOINIT;
+  }
+  return token;
+}
+
+bool sdReadBytes(uint8_t pdrv, char *buffer, int length) {
+  char token;
+  unsigned short crc;
+  ardu_sdcard_t *card = s_cards[pdrv];
+
+  uint32_t start = millis();
+  do {
+    token = card->spi->transfer(0xFF);
+  } while (token == 0xFF && (millis() - start) < 500);
+
+  if (token != 0xFE) {
+    return false;
+  }
+
+  card->spi->transferBytes(NULL, (uint8_t *)buffer, length);
+  crc = card->spi->transfer16(0xFFFF);
+  return (!card->supports_crc || crc == CRC16(buffer, length));
+}
+
+char sdWriteBytes(uint8_t pdrv, const char *buffer, char token) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  unsigned short crc = (card->supports_crc) ? CRC16(buffer, 512) : 0xFFFF;
+  if (!sdWait(pdrv, 500)) {
+    return 0;
+  }
+
+  card->spi->write(token);
+  card->spi->writeBytes((uint8_t *)buffer, 512);
+  card->spi->write16(crc);
+  return (card->spi->transfer(0xFF) & 0x1F);
+}
+
+/*
+ * SPI SDCARD Communication
+ * */
+
+char sdTransaction(uint8_t pdrv, char cmd, unsigned int arg, unsigned int *resp) {
+  if (!sdSelectCard(pdrv)) {
+    return 0xFF;
+  }
+  char token = sdCommand(pdrv, cmd, arg, resp);
+  sdDeselectCard(pdrv);
+  return token;
+}
+
+bool sdReadSector(uint8_t pdrv, char *buffer, unsigned long long sector) {
+  for (int f = 0; f < 3; f++) {
+    if (!sdSelectCard(pdrv)) {
+      return false;
+    }
+    if (!sdCommand(pdrv, READ_BLOCK_SINGLE, (s_cards[pdrv]->type == CARD_SDHC) ? sector : sector << 9, NULL)) {
+      bool success = sdReadBytes(pdrv, buffer, 512);
+      sdDeselectCard(pdrv);
+      if (success) {
+        return true;
+      }
+    } else {
+      break;
+    }
+  }
+  sdDeselectCard(pdrv);
+  return false;
+}
+
+bool sdReadSectors(uint8_t pdrv, char *buffer, unsigned long long sector, int count) {
+  for (int f = 0; f < 3;) {
+    if (!sdSelectCard(pdrv)) {
+      return false;
+    }
+
+    if (!sdCommand(pdrv, READ_BLOCK_MULTIPLE, (s_cards[pdrv]->type == CARD_SDHC) ? sector : sector << 9, NULL)) {
+      do {
+        if (!sdReadBytes(pdrv, buffer, 512)) {
+          f++;
+          break;
+        }
+
+        sector++;
+        buffer += 512;
+        f = 0;
+      } while (--count);
+
+      if (sdCommand(pdrv, STOP_TRANSMISSION, 0, NULL)) {
+        log_e("command failed");
+        break;
+      }
+
+      sdDeselectCard(pdrv);
+      if (count == 0) {
+        return true;
+      }
+    } else {
+      break;
+    }
+  }
+  sdDeselectCard(pdrv);
+  return false;
+}
+
+bool sdWriteSector(uint8_t pdrv, const char *buffer, unsigned long long sector) {
+  using roro::SdFault;
+  for (int f = 0; f < 3; f++) {
+    if (!sdSelectCard(pdrv)) {
+      return sdFault(SdFault::Select);  // roro: say why
+    }
+    if (!sdCommand(pdrv, WRITE_BLOCK_SINGLE, (s_cards[pdrv]->type == CARD_SDHC) ? sector : sector << 9, NULL)) {
+      char token = sdWriteBytes(pdrv, buffer, 0xFE);
+      sdDeselectCard(pdrv);
+
+      if (token == 0x0A) {
+        continue;
+      } else if (token == 0x0C) {
+        return sdFault(SdFault::DataToken, token);
+      }
+
+      unsigned int resp;
+      char status = sdTransaction(pdrv, SEND_STATUS, 0, &resp);
+      if (status || resp) {
+        return token != 0x05 ? sdFault(SdFault::DataToken, token, resp) : sdFault(SdFault::Status, status, resp);
+      }
+      return true;
+    } else {
+      break;
+    }
+  }
+  sdDeselectCard(pdrv);
+  return sdFault(SdFault::Command);
+}
+
+bool sdWriteSectors(uint8_t pdrv, const char *buffer, unsigned long long sector, int count) {
+  using roro::SdFault;
+  char token;
+  const char *currentBuffer = buffer;
+  unsigned long long currentSector = sector;
+  int currentCount = count;
+  ardu_sdcard_t *card = s_cards[pdrv];
+  SdFault::Step why = SdFault::Command;  // roro: what stopped it, for the last return
+  uint8_t whyToken = 0;
+
+  for (int f = 0; f < 3;) {
+    if (card->type != CARD_MMC) {
+      char refused = sdTransaction(pdrv, SET_WR_BLK_ERASE_COUNT, currentCount, NULL);
+      if (refused) {
+        return sdFault(SdFault::EraseCount, refused);
+      }
+    }
+
+    if (!sdSelectCard(pdrv)) {
+      return sdFault(SdFault::Select);
+    }
+
+    if (!sdCommand(pdrv, WRITE_BLOCK_MULTIPLE, (card->type == CARD_SDHC) ? currentSector : currentSector << 9, NULL)) {
+      do {
+        token = sdWriteBytes(pdrv, currentBuffer, 0xFC);
+        if (token != 0x05) {
+          f++;
+          break;
+        }
+        currentBuffer += 512;
+        f = 0;
+      } while (--currentCount);
+
+      if (!sdWait(pdrv, 500)) {
+        why = SdFault::BusyAfter;
+        break;
+      }
+
+      if (currentCount == 0) {
+        sdStop(pdrv);
+        card->spi->transfer(0xFF);  // roro: the byte the card takes to go busy after Stop Tran (#21)
+        sdDeselectCard(pdrv);
+
+        unsigned int resp;
+        char status = sdTransaction(pdrv, SEND_STATUS, 0, &resp);
+        if (status || resp) {
+          return sdFault(SdFault::Status, status, resp);
+        }
+        return true;
+      } else {
+        if (sdCommand(pdrv, STOP_TRANSMISSION, 0, NULL)) {
+          why = SdFault::StopCommand;
+          whyToken = token;
+          break;
+        }
+
+        if (token == 0x0A) {
+          sdDeselectCard(pdrv);
+          unsigned int writtenBlocks = 0;
+          if (card->type != CARD_MMC && sdSelectCard(pdrv)) {
+            if (!sdCommand(pdrv, SEND_NUM_WR_BLOCKS, 0, NULL)) {
+              char acmdData[4];
+              if (sdReadBytes(pdrv, acmdData, 4)) {
+                writtenBlocks = acmdData[0] << 24;
+                writtenBlocks |= acmdData[1] << 16;
+                writtenBlocks |= acmdData[2] << 8;
+                writtenBlocks |= acmdData[3];
+              }
+            }
+            sdDeselectCard(pdrv);
+          }
+          currentBuffer = buffer + (writtenBlocks << 9);
+          currentSector = sector + writtenBlocks;
+          currentCount = count - writtenBlocks;
+          continue;
+        } else {
+          why = SdFault::DataToken;
+          whyToken = token;
+          break;
+        }
+      }
+    } else {
+      break;
+    }
+  }
+  sdDeselectCard(pdrv);
+  return sdFault(why, whyToken);
+}
+
+unsigned long sdGetSectorsCount(uint8_t pdrv) {
+  for (int f = 0; f < 3; f++) {
+    if (!sdSelectCard(pdrv)) {
+      return 0;
+    }
+
+    if (!sdCommand(pdrv, SEND_CSD, 0, NULL)) {
+      char csd[16];
+      bool success = sdReadBytes(pdrv, csd, 16);
+      sdDeselectCard(pdrv);
+      if (success) {
+        if ((csd[0] >> 6) == 0x01) {
+          unsigned long size = (((unsigned long)(csd[7] & 0x3F) << 16) | ((unsigned long)csd[8] << 8) | csd[9]) + 1;
+          return size << 10;
+        }
+        unsigned long size = (((unsigned long)(csd[6] & 0x03) << 10) | ((unsigned long)csd[7] << 2) | ((csd[8] & 0xC0) >> 6)) + 1;
+        size <<= ((((csd[9] & 0x03) << 1) | ((csd[10] & 0x80) >> 7)) + 2);
+        size <<= (csd[5] & 0x0F);
+        return size >> 9;
+      }
+    } else {
+      break;
+    }
+  }
+
+  sdDeselectCard(pdrv);
+  return 0;
+}
+
+namespace {
+
+struct AcquireSPI {
+  ardu_sdcard_t *card;
+  explicit AcquireSPI(ardu_sdcard_t *card) : card(card) {
+    card->spi->beginTransaction(SPISettings(card->frequency, MSBFIRST, SPI_MODE0));
+  }
+  AcquireSPI(ardu_sdcard_t *card, int frequency) : card(card) {
+    card->spi->beginTransaction(SPISettings(frequency, MSBFIRST, SPI_MODE0));
+  }
+  ~AcquireSPI() {
+    card->spi->endTransaction();
+  }
+
+private:
+  AcquireSPI(AcquireSPI const &);
+  AcquireSPI &operator=(AcquireSPI const &);
+};
+
+}  // namespace
+
+/*
+ * FATFS API
+ * */
+
+/**
+ * @brief Initialize an SD card for use with FatFs
+ *
+ * This function implements the complete SD card initialization sequence according to
+ * the SD card specification. It performs card detection, type identification,
+ * and configuration for SPI mode operation.
+ *
+ * The initialization sequence follows the SD card protocol (SPI mode, aligned with IDF):
+ * 1. Power-up sequence with 74+ clock cycles
+ * 2. Two GO_IDLE_STATE attempts to enter SPI mode
+ * 3. CRC_ON_OFF to enable CRC checking (with retry)
+ * 4. SEND_IF_COND to identify SDHC/SDXC cards
+ * 5. APP_OP_COND / SEND_OP_COND (SPI args; timeout >1s)
+ * 6. Card type detection (SD/SDHC/MMC)
+ * 7. Final configuration and sector count retrieval
+ *
+ * @param pdrv Physical drive number (0-9)
+ * @return DSTATUS Status of the initialization (0 = success, STA_NOINIT = failed)
+ */
+DSTATUS ff_sd_initialize(uint8_t pdrv) {
+  char token;
+  unsigned int resp;
+  unsigned int start;
+
+  // Get the card structure for the given drive number
+  ardu_sdcard_t *card = s_cards[pdrv];
+
+  // If the card is already initialized, return its current status
+  if (!(card->status & STA_NOINIT)) {
+    return card->status;
+  }
+
+  // Lock the SPI bus and set it to a low frequency (400kHz) for initialization
+  // Low frequency is required during initialization for reliable communication
+  AcquireSPI card_locked(card, 400000);
+
+  // Step 1: Power-up sequence - Send at least 74 clock cycles with CS high and MOSI high
+  // This is required by the SD card specification to ensure proper card state reset
+  // We send 20 bytes (160 clock cycles) to exceed the minimum requirement
+  digitalWrite(card->ssPin, HIGH);
+  for (uint8_t i = 0; i < 20; i++) {
+    card->spi->transfer(0XFF);
+  }
+
+  // Step 2: Perform two GO_IDLE_STATE (CMD0) attempts in SPI mode.
+  // Per SD Simplified Spec (figure 4-1) / IDF: some cards enter SD mode on the
+  // first attempt, so the first response may fail; the second must succeed.
+  // (sdCommand may also retry internally on no-token/CRC errors.)
+  // Fix mount issue - sdWait fail ignored before each CMD0 attempt
+  digitalWrite(card->ssPin, LOW);
+  if (!sdWait(pdrv, 500)) {
+    log_w("sdWait fail ignored, card initialize continues");
+  }
+  (void)sdCommand(pdrv, GO_IDLE_STATE, 0, NULL);
+  sdDeselectCard(pdrv);
+  delay(sd_go_idle_delay_ms);
+
+  digitalWrite(card->ssPin, LOW);
+  if (!sdWait(pdrv, 500)) {
+    log_w("sdWait fail ignored, card initialize continues");
+  }
+  if (sdCommand(pdrv, GO_IDLE_STATE, 0, NULL) != 1) {
+    sdDeselectCard(pdrv);
+    log_w("GO_IDLE_STATE failed");
+    goto unknown_card;
+  }
+  sdDeselectCard(pdrv);
+  delay(sd_go_idle_delay_ms);
+
+  // Step 3: Configure CRC checking
+  // Enable CRC for data transfers in SPI mode (required for reliable communication).
+  // Some cards reject the first CRC_ON_OFF; retry once (same as IDF).
+  token = sdTransaction(pdrv, CRC_ON_OFF, 1, NULL);
+  if (token != 1 && token != 0x5) {
+    delay(10);
+    token = sdTransaction(pdrv, CRC_ON_OFF, 1, NULL);
+  }
+  if (token == 0x5) {
+    // Old card that doesn't support CRC - disable CRC checking
+    card->supports_crc = false;
+  } else if (token != 1) {
+    log_w("CRC_ON_OFF failed: %u", token);
+    goto unknown_card;
+  }
+
+  // Step 4: Card type detection and initialization
+  // Try to identify SDHC/SDXC cards using SEND_IF_COND command
+  if (sdTransaction(pdrv, SEND_IF_COND, 0x1AA, &resp) == 1) {
+    // Card responded to SEND_IF_COND - likely SDHC/SDXC
+    if ((resp & 0xFFF) != 0x1AA) {
+      log_w("SEND_IF_COND failed: %03" PRIX32, (uint32_t)(resp & 0xFFF));
+      goto unknown_card;
+    }
+
+    // Read Operating Conditions Register to check card capabilities
+    if (sdTransaction(pdrv, READ_OCR, 0, &resp) != 1 || !(resp & (1 << 20))) {
+      log_w("READ_OCR failed: %X", resp);
+      goto unknown_card;
+    }
+
+    // Send APP_OP_COND to set operating conditions for SDHC/SDXC.
+    // In SPI mode only HCS (bit 30) is valid; voltage bits must be 0 (same as IDF).
+    // Timeout must be >1s per SD spec (IDF uses ~3s).
+    start = millis();
+    do {
+      token = sdTransaction(pdrv, APP_OP_COND, 0x40000000, NULL);
+    } while (token == 1 && (millis() - start) < sd_op_cond_timeout_ms);
+
+    if (token) {
+      log_w("APP_OP_COND failed: %u", token);
+      goto unknown_card;
+    }
+
+    // Determine if it's SDHC (high capacity) or regular SD
+    if (!sdTransaction(pdrv, READ_OCR, 0, &resp)) {
+      if (resp & (1 << 30)) {
+        card->type = CARD_SDHC;  // High capacity card (SDHC/SDXC)
+      } else {
+        card->type = CARD_SD;  // Standard capacity card
+      }
+    } else {
+      log_w("READ_OCR failed: %X", resp);
+      goto unknown_card;
+    }
+  } else {
+    // Card didn't respond to SEND_IF_COND - try SD or MMC initialization
+    if (sdTransaction(pdrv, READ_OCR, 0, &resp) != 1 || !(resp & (1 << 20))) {
+      log_w("READ_OCR failed: %X", resp);
+      goto unknown_card;
+    }
+
+    // Try SD card initialization first (SPI mode: ACMD41 arg must be 0)
+    start = millis();
+    do {
+      token = sdTransaction(pdrv, APP_OP_COND, 0, NULL);
+    } while (token == 0x01 && (millis() - start) < sd_op_cond_timeout_ms);
+
+    if (!token) {
+      card->type = CARD_SD;  // Standard SD card
+    } else {
+      // Try MMC card initialization (SPI mode: CMD1 arg must be 0)
+      start = millis();
+      do {
+        token = sdTransaction(pdrv, SEND_OP_COND, 0, NULL);
+      } while (token != 0x00 && (millis() - start) < sd_op_cond_timeout_ms);
+
+      if (token == 0x00) {
+        card->type = CARD_MMC;  // MMC card
+      } else {
+        log_w("SEND_OP_COND failed: %u", token);
+        goto unknown_card;
+      }
+    }
+  }
+
+  // Step 5: Clear card detection for SD cards (not needed for MMC)
+  if (card->type != CARD_MMC) {
+    if (sdTransaction(pdrv, APP_CLR_CARD_DETECT, 0, NULL)) {
+      log_w("APP_CLR_CARD_DETECT failed");
+      goto unknown_card;
+    }
+  }
+
+  // Step 6: Set block length for non-SDHC cards
+  // SDHC cards have fixed 512-byte blocks, others need explicit block length setting
+  if (card->type != CARD_SDHC) {
+    if (sdTransaction(pdrv, SET_BLOCKLEN, 512, NULL) != 0x00) {
+      log_w("SET_BLOCKLEN failed");
+      goto unknown_card;
+    }
+  }
+
+  // Step 7: Get card capacity and finalize initialization
+  card->sectors = sdGetSectorsCount(pdrv);
+
+  // Limit frequency to 25MHz for compatibility (SD spec maximum for non-UHS cards)
+  if (card->frequency > 25000000) {
+    card->frequency = 25000000;
+  }
+
+  // Mark card as initialized
+  card->status &= ~STA_NOINIT;
+  return card->status;
+
+unknown_card:
+  // Mark card as unknown type if initialization failed
+  card->type = CARD_UNKNOWN;
+  return card->status;
+}
+
+DSTATUS ff_sd_status(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  AcquireSPI lock(card);
+
+  if (sdTransaction(pdrv, SEND_STATUS, 0, NULL)) {
+    log_e("Check status failed");
+    return STA_NOINIT;
+  }
+  return s_cards[pdrv]->status;
+}
+
+DRESULT ff_sd_read(uint8_t pdrv, uint8_t *buffer, DWORD sector, UINT count) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (card->status & STA_NOINIT) {
+    return RES_NOTRDY;
+  }
+  DRESULT res = RES_OK;
+
+  AcquireSPI lock(card);
+
+  if (count > 1) {
+    res = sdReadSectors(pdrv, (char *)buffer, sector, count) ? RES_OK : RES_ERROR;
+  } else {
+    res = sdReadSector(pdrv, (char *)buffer, sector) ? RES_OK : RES_ERROR;
+  }
+  return res;
+}
+
+DRESULT ff_sd_write(uint8_t pdrv, const uint8_t *buffer, DWORD sector, UINT count) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (card->status & STA_NOINIT) {
+    return RES_NOTRDY;
+  }
+
+  if (card->status & STA_PROTECT) {
+    return RES_WRPRT;
+  }
+  DRESULT res = RES_OK;
+
+  AcquireSPI lock(card);
+
+  if (count > 1) {
+    res = sdWriteSectors(pdrv, (const char *)buffer, sector, count) ? RES_OK : RES_ERROR;
+  } else {
+    res = sdWriteSector(pdrv, (const char *)buffer, sector) ? RES_OK : RES_ERROR;
+  }
+  return res;
+}
+
+DRESULT ff_sd_ioctl(uint8_t pdrv, uint8_t cmd, void *buff) {
+  switch (cmd) {
+    case CTRL_SYNC:
+    {
+      AcquireSPI lock(s_cards[pdrv]);
+      if (sdSelectCard(pdrv)) {
+        sdDeselectCard(pdrv);
+        return RES_OK;
+      }
+    }
+      return RES_ERROR;
+    case GET_SECTOR_COUNT: *((unsigned long *)buff) = s_cards[pdrv]->sectors; return RES_OK;
+    case GET_SECTOR_SIZE:  *((WORD *)buff) = 512; return RES_OK;
+    case GET_BLOCK_SIZE:   *((uint32_t *)buff) = 1; return RES_OK;
+  }
+  return RES_PARERR;
+}
+
+bool sd_read_raw(uint8_t pdrv, uint8_t *buffer, DWORD sector) {
+  return ff_sd_read(pdrv, buffer, sector, 1) == ESP_OK;
+}
+
+bool sd_write_raw(uint8_t pdrv, uint8_t *buffer, DWORD sector) {
+  return ff_sd_write(pdrv, buffer, sector, 1) == ESP_OK;
+}
+
+/*
+ * Public methods
+ * */
+
+uint8_t sdcard_uninit(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (pdrv >= FF_VOLUMES || card == NULL) {
+    return 1;
+  }
+  {
+    AcquireSPI lock(card);
+    sdTransaction(pdrv, GO_IDLE_STATE, 0, NULL);
+  }  // lock is destructed here
+  ff_diskio_register(pdrv, NULL);
+  s_cards[pdrv] = NULL;
+  esp_err_t err = ESP_OK;
+  if (card->base_path) {
+    err = esp_vfs_fat_unregister_path(card->base_path);
+    free(card->base_path);
+  }
+  free(card);
+  return err;
+}
+
+uint8_t sdcard_init(uint8_t cs, SPIClass *spi, int hz) {
+
+  uint8_t pdrv = 0xFF;
+  if (ff_diskio_get_drive(&pdrv) != ESP_OK || pdrv == 0xFF) {
+    return pdrv;
+  }
+
+  ardu_sdcard_t *card = (ardu_sdcard_t *)malloc(sizeof(ardu_sdcard_t));
+  if (!card) {
+    return 0xFF;
+  }
+
+  card->base_path = NULL;
+  card->frequency = hz;
+  card->spi = spi;
+  card->ssPin = digitalPinToGPIONumber(cs);
+
+  card->supports_crc = true;
+  card->type = CARD_NONE;
+  card->status = STA_NOINIT;
+
+  pinMode(card->ssPin, OUTPUT);
+  digitalWrite(card->ssPin, HIGH);
+  perimanSetPinBusExtraType(card->ssPin, "SD_SS");
+
+  s_cards[pdrv] = card;
+
+  static const ff_diskio_impl_t sd_impl = {
+    .init = &ff_sd_initialize, .status = &ff_sd_status, .read = &ff_sd_read, .write = &ff_sd_write, .ioctl = &ff_sd_ioctl
+  };
+  ff_diskio_register(pdrv, &sd_impl);
+
+  return pdrv;
+}
+
+uint8_t sdcard_unmount(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (pdrv >= FF_VOLUMES || card == NULL) {
+    return 1;
+  }
+  card->status |= STA_NOINIT;
+  card->type = CARD_NONE;
+
+  char drv[3] = {(char)('0' + pdrv), ':', 0};
+  f_mount(NULL, drv, 0);
+  return 0;
+}
+
+bool sdcard_mount(uint8_t pdrv, const char *path, uint8_t max_files, bool format_if_empty) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (pdrv >= FF_VOLUMES || card == NULL) {
+    return false;
+  }
+
+  if (card->base_path) {
+    free(card->base_path);
+  }
+  card->base_path = strdup(path);
+
+  FATFS *fs;
+  char drv[3] = {(char)('0' + pdrv), ':', 0};
+
+#if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(6, 0, 0)
+  esp_err_t err = esp_vfs_fat_register(path, drv, max_files, &fs);
+#else
+  esp_vfs_fat_conf_t conf = {.base_path = path, .fat_drive = drv, .max_files = max_files};
+  esp_err_t err = esp_vfs_fat_register(&conf, &fs);
+#endif
+
+  if (err == ESP_ERR_INVALID_STATE) {
+    log_e("esp_vfs_fat_register failed 0x(%x): SD is registered.", err);
+    return false;
+  } else if (err != ESP_OK) {
+    log_e("esp_vfs_fat_register failed 0x(%x)", err);
+    return false;
+  }
+
+  FRESULT res = f_mount(fs, drv, 1);
+  if (res != FR_OK) {
+    log_e("f_mount failed: %s", fferr2str[res]);
+    if (res == 13 && format_if_empty) {
+      BYTE *work = (BYTE *)malloc(sizeof(BYTE) * FF_MAX_SS);
+      if (!work) {
+        log_e("alloc for f_mkfs failed");
+        return false;
+      }
+      //FRESULT f_mkfs (const TCHAR* path, const MKFS_PARM* opt, void* work, UINT len);
+      const MKFS_PARM opt = {(BYTE)FM_ANY, 0, 0, 0, 0};
+      res = f_mkfs(drv, &opt, work, sizeof(BYTE) * FF_MAX_SS);
+      free(work);
+      if (res != FR_OK) {
+        log_e("f_mkfs failed: %s", fferr2str[res]);
+        esp_vfs_fat_unregister_path(path);
+        return false;
+      }
+      res = f_mount(fs, drv, 1);
+      if (res != FR_OK) {
+        log_e("f_mount failed: %s", fferr2str[res]);
+        esp_vfs_fat_unregister_path(path);
+        return false;
+      }
+    } else {
+      esp_vfs_fat_unregister_path(path);
+      return false;
+    }
+  }
+  AcquireSPI lock(card);
+  card->sectors = sdGetSectorsCount(pdrv);
+  return true;
+}
+
+uint32_t sdcard_num_sectors(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (pdrv >= FF_VOLUMES || card == NULL) {
+    return 0;
+  }
+  return card->sectors;
+}
+
+uint32_t sdcard_sector_size(uint8_t pdrv) {
+  if (pdrv >= FF_VOLUMES || s_cards[pdrv] == NULL) {
+    return 0;
+  }
+  return 512;
+}
+
+// roro: the card's CID. CMD10 in SPI mode (the enum's SEND_CID, 2, is the SD-mode command).
+namespace roro {
+bool sdReadCid(uint8_t cid[16]) {
+  for (uint8_t pdrv = 0; pdrv < FF_VOLUMES; ++pdrv) {
+    ardu_sdcard_t *card = s_cards[pdrv];
+    if (!card) {
+      continue;
+    }
+    AcquireSPI lock(card);
+    if (!sdSelectCard(pdrv)) {
+      return false;
+    }
+    bool ok = !sdCommand(pdrv, 10, 0, NULL) && sdReadBytes(pdrv, (char *)cid, 16);
+    sdDeselectCard(pdrv);
+    return ok;
+  }
+  return false;
+}
+}  // namespace roro
+
+sdcard_type_t sdcard_type(uint8_t pdrv) {
+  ardu_sdcard_t *card = s_cards[pdrv];
+  if (pdrv >= FF_VOLUMES || card == NULL) {
+    return CARD_NONE;
+  }
+  return card->type;
+}
@@ -0,0 +1,34 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _SD_DISKIO_H_
+#define _SD_DISKIO_H_
+
+#include "Arduino.h"
+#include "SPI.h"
+#include "sd_defines.h"
+// #include "diskio.h"
+
+uint8_t sdcard_init(uint8_t cs, SPIClass *spi, int hz);
+uint8_t sdcard_uninit(uint8_t pdrv);
+
+bool sdcard_mount(uint8_t pdrv, const char *path, uint8_t max_files, bool format_if_empty);
+uint8_t sdcard_unmount(uint8_t pdrv);
+
+sdcard_type_t sdcard_type(uint8_t pdrv);
+uint32_t sdcard_num_sectors(uint8_t pdrv);
+uint32_t sdcard_sector_size(uint8_t pdrv);
+bool sd_read_raw(uint8_t pdrv, uint8_t *buffer, uint32_t sector);
+bool sd_write_raw(uint8_t pdrv, uint8_t *buffer, uint32_t sector);
+
+#endif /* _SD_DISKIO_H_ */
@@ -0,0 +1,61 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2014 Neil Thiessen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const char m_CRC7Table[] = {0x00, 0x09, 0x12, 0x1B, 0x24, 0x2D, 0x36, 0x3F, 0x48, 0x41, 0x5A, 0x53, 0x6C, 0x65, 0x7E, 0x77, 0x19, 0x10, 0x0B, 0x02, 0x3D, 0x34,
+                            0x2F, 0x26, 0x51, 0x58, 0x43, 0x4A, 0x75, 0x7C, 0x67, 0x6E, 0x32, 0x3B, 0x20, 0x29, 0x16, 0x1F, 0x04, 0x0D, 0x7A, 0x73, 0x68, 0x61,
+                            0x5E, 0x57, 0x4C, 0x45, 0x2B, 0x22, 0x39, 0x30, 0x0F, 0x06, 0x1D, 0x14, 0x63, 0x6A, 0x71, 0x78, 0x47, 0x4E, 0x55, 0x5C, 0x64, 0x6D,
+                            0x76, 0x7F, 0x40, 0x49, 0x52, 0x5B, 0x2C, 0x25, 0x3E, 0x37, 0x08, 0x01, 0x1A, 0x13, 0x7D, 0x74, 0x6F, 0x66, 0x59, 0x50, 0x4B, 0x42,
+                            0x35, 0x3C, 0x27, 0x2E, 0x11, 0x18, 0x03, 0x0A, 0x56, 0x5F, 0x44, 0x4D, 0x72, 0x7B, 0x60, 0x69, 0x1E, 0x17, 0x0C, 0x05, 0x3A, 0x33,
+                            0x28, 0x21, 0x4F, 0x46, 0x5D, 0x54, 0x6B, 0x62, 0x79, 0x70, 0x07, 0x0E, 0x15, 0x1C, 0x23, 0x2A, 0x31, 0x38, 0x41, 0x48, 0x53, 0x5A,
+                            0x65, 0x6C, 0x77, 0x7E, 0x09, 0x00, 0x1B, 0x12, 0x2D, 0x24, 0x3F, 0x36, 0x58, 0x51, 0x4A, 0x43, 0x7C, 0x75, 0x6E, 0x67, 0x10, 0x19,
+                            0x02, 0x0B, 0x34, 0x3D, 0x26, 0x2F, 0x73, 0x7A, 0x61, 0x68, 0x57, 0x5E, 0x45, 0x4C, 0x3B, 0x32, 0x29, 0x20, 0x1F, 0x16, 0x0D, 0x04,
+                            0x6A, 0x63, 0x78, 0x71, 0x4E, 0x47, 0x5C, 0x55, 0x22, 0x2B, 0x30, 0x39, 0x06, 0x0F, 0x14, 0x1D, 0x25, 0x2C, 0x37, 0x3E, 0x01, 0x08,
+                            0x13, 0x1A, 0x6D, 0x64, 0x7F, 0x76, 0x49, 0x40, 0x5B, 0x52, 0x3C, 0x35, 0x2E, 0x27, 0x18, 0x11, 0x0A, 0x03, 0x74, 0x7D, 0x66, 0x6F,
+                            0x50, 0x59, 0x42, 0x4B, 0x17, 0x1E, 0x05, 0x0C, 0x33, 0x3A, 0x21, 0x28, 0x5F, 0x56, 0x4D, 0x44, 0x7B, 0x72, 0x69, 0x60, 0x0E, 0x07,
+                            0x1C, 0x15, 0x2A, 0x23, 0x38, 0x31, 0x46, 0x4F, 0x54, 0x5D, 0x62, 0x6B, 0x70, 0x79};
+
+char CRC7(const char *data, int length) {
+  char crc = 0;
+  for (int i = 0; i < length; i++) {
+    crc = m_CRC7Table[(crc << 1) ^ data[i]];
+  }
+  return crc;
+}
+
+const unsigned short m_CRC16Table[256] = {
+  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7, 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF, 0x1231, 0x0210, 0x3273,
+  0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6, 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE, 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7,
+  0x44A4, 0x5485, 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D, 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4, 0xB75B,
+  0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC, 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823, 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF,
+  0x8948, 0x9969, 0xA90A, 0xB92B, 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12, 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B,
+  0xAB1A, 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41, 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49, 0x7E97, 0x6EB6,
+  0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70, 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78, 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C,
+  0xC12D, 0xF14E, 0xE16F, 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067, 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
+  0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256, 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D, 0x34E2, 0x24C3, 0x14A0,
+  0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C, 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676,
+  0x4615, 0x5634, 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB, 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3, 0xCB7D,
+  0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A, 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92, 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D,
+  0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9, 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1, 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9,
+  0x9FF8, 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
+};
+
+unsigned short CRC16(const char *data, int length) {
+  unsigned short crc = 0;
+  for (int i = 0; i < length; i++) {
+    crc = (crc << 8) ^ m_CRC16Table[((crc >> 8) ^ data[i]) & 0x00FF];
+  }
+  return crc;
+}
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <cstdint>
+
+namespace roro {
+
+// Why the SD driver last gave up on a write (see sd_diskio.cpp, issue #21). The framework's driver
+// fails without saying why; ours records it.
+struct SdFault {
+    enum Step : uint8_t {
+        None,
+        EraseCount,   // ACMD23 before a multi-block write was refused
+        Select,       // the card stayed busy for 500 ms
+        Command,      // the write command itself was refused
+        DataToken,    // the card's answer to a data block: 0x0B CRC error, 0x0D write error
+        BusyAfter,    // still busy 500 ms after the last block
+        Status,       // CMD13 after the write reported an error (resp)
+        StopCommand,  // CMD12 after a rejected block was refused
+    };
+    Step step = None;
+    uint8_t token = 0;   // the driver's or the card's answer at that step
+    uint32_t resp = 0;   // CMD13's status bits, for Status
+    uint32_t count = 0;  // failed writes since boot
+    uint32_t retried = 0;  // blocks resent after a CRC error, since boot
+};
+
+SdFault sdLastFault();
+
+// The mounted card's identity register (CID, CMD10): who made it, its name, serial and date.
+// Call it where card access is allowed (the storage task).
+bool sdReadCid(uint8_t cid[16]);
+
+}  // namespace roro
@@ -0,0 +1,97 @@
+#include "ipv4.h"
+
+#include <cstdio>
+
+namespace roro::net {
+
+bool parseIpv4(const std::string& text, uint32_t& out) {
+    uint32_t value = 0;
+    int parts = 0, digits = 0, part = 0;
+    for (char c : text) {
+        if (c >= '0' && c <= '9') {
+            if (++digits > 3) return false;
+            part = part * 10 + (c - '0');
+            if (part > 255) return false;
+        } else if (c == '.') {
+            if (digits == 0 || ++parts > 3) return false;
+            value = value << 8 | part;
+            part = digits = 0;
+        } else {
+            return false;
+        }
+    }
+    if (digits == 0 || parts != 3) return false;
+    out = value << 8 | part;
+    return true;
+}
+
+std::string formatIpv4(uint32_t a) {
+    char s[16];
+    std::snprintf(s, sizeof s, "%u.%u.%u.%u", static_cast<unsigned>(a >> 24), static_cast<unsigned>(a >> 16 & 255),
+                  static_cast<unsigned>(a >> 8 & 255), static_cast<unsigned>(a & 255));
+    return s;
+}
+
+uint32_t maskOf(int prefix) { return prefix <= 0 ? 0 : prefix >= 32 ? 0xFFFFFFFFu : ~0u << (32 - prefix); }
+
+std::string checkFixed(const FixedIp& f) {
+    if (f.prefix < 1 || f.prefix > 30) return "The prefix must be 1 to 30";
+    if (f.address == 0) return "0.0.0.0 isn't an address a device can have";
+    uint32_t mask = maskOf(f.prefix), network = f.address & mask, broadcast = network | ~mask;
+    if (f.address == network) return formatIpv4(f.address) + " is the network's own address";
+    if (f.address == broadcast) return formatIpv4(f.address) + " is the broadcast address";
+    if (f.gateway == 0) return "";
+    if (f.gateway == f.address) return "The gateway can't be this device's address";
+    if ((f.gateway & mask) != network)
+        return "The gateway " + formatIpv4(f.gateway) + " isn't in " + formatIpv4(network) + "/" + std::to_string(f.prefix);
+    if (f.gateway == broadcast) return "The gateway " + formatIpv4(f.gateway) + " is the broadcast address";
+    if (f.gateway == network) return "The gateway " + formatIpv4(f.gateway) + " is the network's own address";
+    return "";
+}
+
+std::string parseFixed(const std::string& text, FixedIp& out) {
+    size_t slash = text.find('/');
+    if (slash == std::string::npos) return "Write it as address/prefix, then the gateway if there is one";
+    size_t space = text.find(' ', slash);
+    std::string address = text.substr(0, slash);
+    std::string prefix = text.substr(slash + 1, space == std::string::npos ? std::string::npos : space - slash - 1);
+    std::string gateway = space == std::string::npos ? "" : text.substr(space + 1);
+    FixedIp f;
+    if (!parseIpv4(address, f.address)) return address + " isn't an IPv4 address";
+    int p = 0;
+    if (prefix.empty() || prefix.size() > 2) return "The prefix must be 1 to 30";
+    for (char c : prefix) {
+        if (c < '0' || c > '9') return "The prefix must be 1 to 30";
+        p = p * 10 + (c - '0');
+    }
+    f.prefix = static_cast<uint8_t>(p);
+    if (!gateway.empty() && !parseIpv4(gateway, f.gateway)) return gateway + " isn't an IPv4 address";
+    std::string why = checkFixed(f);
+    if (why.empty()) out = f;
+    return why;
+}
+
+std::string formatFixed(const FixedIp& f) {
+    std::string s = formatIpv4(f.address) + "/" + std::to_string(f.prefix);
+    if (f.gateway) s += " " + formatIpv4(f.gateway);
+    return s;
+}
+
+bool validHost(const std::string& text) {
+    if (text.empty() || text.size() > 63) return false;
+    uint32_t ignored;
+    if (parseIpv4(text, ignored)) return true;
+    bool allNumeric = true;  // digits and dots only, but not an address: "1.2.3", "999.1.1.1"
+    char previous = '.';
+    for (char c : text) {
+        bool letter = (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'), digit = c >= '0' && c <= '9';
+        if (!letter && !digit && c != '-' && c != '.') return false;
+        if (c == '.' && (previous == '.' || previous == '-')) return false;  // empty label, or one ending in '-'
+        if (c == '-' && previous == '.') return false;                       // a label starting with '-'
+        if (letter || c == '-') allNumeric = false;
+        previous = c;
+    }
+    return previous != '.' && previous != '-' && !allNumeric;
+}
+
+}  // namespace roro::net
@@ -0,0 +1,30 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace roro::net {
+
+// IPv4 addresses as 32-bit numbers, most significant byte first: 10.39.39.12 is 0x0A27270C.
+bool parseIpv4(const std::string& text, uint32_t& out);  // strict: four decimal numbers, 0 to 255
+std::string formatIpv4(uint32_t address);
+uint32_t maskOf(int prefix);  // 24 -> 255.255.255.0
+
+// A Saved Network's Fixed setting (S1, Q105 to Q107). gateway 0: none.
+struct FixedIp {
+    uint32_t address = 0;
+    uint8_t prefix = 24;
+    uint32_t gateway = 0;
+};
+
+// "" when a device can use it, otherwise why not, for a human (Q111).
+std::string checkFixed(const FixedIp& f);
+
+// "address/prefix [gateway]", as typed on the console and kept in flash. parseFixed() also checks.
+std::string parseFixed(const std::string& text, FixedIp& out);
+std::string formatFixed(const FixedIp& f);
+
+// An IPv4 address or a host name, as an NTP server may be (Q110).
+bool validHost(const std::string& text);
+
+}  // namespace roro::net
@@ -1,5 +1,7 @@
 #include "settings.h"

+#include "ipv4.h"
+
 namespace roro {

 namespace {
@@ -32,6 +34,11 @@ const Definition kDefinitions[] = {
    {"gnss_on", Kind::Bool, 1, nullptr, 0, 1},
    {"coord_dms", Kind::Bool, 0, nullptr, 0, 1},
    {"lora_preset", Kind::Int, 0, nullptr, 0, 6},  // LongFast first
+    {"dns1", Kind::String, 0, "9.9.9.9", 7, 15},  // Quad9
+    {"dns2", Kind::String, 0, "1.1.1.1", 0, 15},  // Cloudflare
+    {"dns_always", Kind::Bool, 0, nullptr, 0, 1},
+    {"ntp1", Kind::String, 0, "pool.ntp.org", 1, 63},
+    {"ntp2", Kind::String, 0, "time.cloudflare.com", 0, 63},
 };
 static_assert(sizeof(kDefinitions) / sizeof(kDefinitions[0]) == static_cast<size_t>(Setting::Count),
              "every Setting needs a definition");
@@ -84,6 +91,11 @@ bool Settings::validString(Setting s, const std::string& value) const {
            if (value == region) return true;
        return false;
    }
+    uint32_t address;
+    if (s == Setting::Dns1) return net::parseIpv4(value, address);
+    if (s == Setting::Dns2) return value.empty() || net::parseIpv4(value, address);
+    if (s == Setting::Ntp1) return net::validHost(value);
+    if (s == Setting::Ntp2) return value.empty() || net::validHost(value);
    return true;
 }

@@ -24,6 +24,11 @@ enum class Setting : uint8_t {
    GnssEnabled,      // bool: the GNSS Service reads the receiver (M2, Q58)
    CoordinatesDms,   // bool: show degrees, minutes and seconds instead of decimal degrees (Q64)
    LoraPreset,       // int: the LoRa Scanner's Meshtastic preset, an index into the EU868 list (M3, Q95)
+    Dns1,             // string: the first DNS server, an IPv4 address (S1, Q108, Q109)
+    Dns2,             // string: the second, or empty
+    DnsAlways,        // bool: use them on Automatic (DHCP) networks too, instead of DHCP's
+    Ntp1,             // string: the first NTP server, a host name or an IPv4 address (S1, Q110)
+    Ntp2,             // string: the second, or empty
    Count
 };

@@ -0,0 +1,53 @@
+#include "sd_card_id.h"
+
+#include <cstdio>
+
+namespace roro {
+
+namespace {
+char printable(uint8_t b) { return b >= 0x20 && b < 0x7F ? static_cast<char>(b) : '?'; }
+}  // namespace
+
+SdCardId parseSdCid(const uint8_t cid[16]) {
+    SdCardId id;
+    id.manufacturer = cid[0];
+    for (int i = 0; i < 2; ++i) id.oem[i] = printable(cid[1 + i]);
+    for (int i = 0; i < 5; ++i) id.product[i] = printable(cid[3 + i]);
+    id.revisionMajor = cid[8] >> 4;
+    id.revisionMinor = cid[8] & 0x0F;
+    id.serial = static_cast<uint32_t>(cid[9]) << 24 | cid[10] << 16 | cid[11] << 8 | cid[12];
+    // 4 reserved bits, 8 bits of year since 2000, 4 bits of month.
+    id.year = 2000 + (((cid[13] & 0x0F) << 4) | (cid[14] >> 4));
+    id.month = cid[14] & 0x0F;
+    return id;
+}
+
+const char* sdManufacturerName(uint8_t id) {
+    switch (id) {
+        case 0x01: return "Panasonic";
+        case 0x02: return "Toshiba/Kioxia";
+        case 0x03: return "SanDisk";
+        case 0x1B: return "Samsung";
+        case 0x1D: return "ADATA";
+        case 0x27: return "Phison";
+        case 0x28: return "Lexar";
+        case 0x31: return "Silicon Power";
+        case 0x41: return "Kingston";
+        case 0x74: return "Transcend";
+        case 0x76: return "Patriot";
+        case 0x82: return "Sony";
+        case 0x9C: return "Angelbird/Hoodman";
+        case 0xAD: return "Longsys/Lexar";
+        default: return "unknown";
+    }
+}
+
+std::string sdCardSummary(const SdCardId& id) {
+    char s[112];
+    std::snprintf(s, sizeof s, "%s (0x%02X) \"%s\" \"%s\" rev %u.%u, serial %08x, made %04d-%02d",
+                  sdManufacturerName(id.manufacturer), id.manufacturer, id.oem, id.product, id.revisionMajor,
+                  id.revisionMinor, static_cast<unsigned>(id.serial), id.year, id.month);
+    return s;
+}
+
+}  // namespace roro
@@ -0,0 +1,27 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace roro {
+
+// What an SD card says it is: its CID register, 16 bytes (SD Physical Layer spec, 5.2).
+struct SdCardId {
+    uint8_t manufacturer = 0;  // assigned by the SD Association; see sdManufacturerName()
+    char oem[3] = {};          // two characters
+    char product[6] = {};      // five characters
+    uint8_t revisionMajor = 0, revisionMinor = 0;
+    uint32_t serial = 0;
+    int year = 0, month = 0;  // manufactured
+};
+
+SdCardId parseSdCid(const uint8_t cid[16]);
+
+// The usual holder of a manufacturer ID. The SD Association doesn't publish its list: these are
+// the commonly reported ones, and resold or counterfeit cards carry whatever their maker chose.
+const char* sdManufacturerName(uint8_t id);
+
+// "SanDisk (0x03) "SD" "SU08G" rev 8.0, serial 1234abcd, made 2014-03".
+std::string sdCardSummary(const SdCardId& id);
+
+}  // namespace roro
@@ -17,6 +17,8 @@ void SavedNetworks::load() {
        int32_t hidden = 0;
        store_.getInt(key(i, "hid").c_str(), hidden);
        net.hidden = hidden != 0;
+        std::string ip;  // "address/prefix [gateway]", or empty for Automatic
+        net.fixed = store_.getString(key(i, "ip").c_str(), ip) && !ip.empty() && net::parseFixed(ip, net.ip).empty();
        networks_.push_back(net);
    }
 }
@@ -40,11 +42,30 @@ std::string SavedNetworks::add(const std::string& ssid, const std::string& passw
        }
    }
    if (count() >= kMax) return "Already 8 saved networks: forget one first";
-    networks_.push_back({ssid, password, hidden});
+    SavedNetwork added;
+    added.ssid = ssid;
+    added.password = password;
+    added.hidden = hidden;
+    networks_.push_back(added);
    save();
    return "";
 }

+std::string SavedNetworks::setIp(const std::string& ssid, const net::FixedIp* fixed) {
+    for (auto& n : networks_) {
+        if (n.ssid != ssid) continue;
+        if (fixed) {
+            std::string why = net::checkFixed(*fixed);
+            if (!why.empty()) return why;
+            n.ip = *fixed;
+        }
+        n.fixed = fixed != nullptr;
+        save();
+        return "";
+    }
+    return "Not a saved network";
+}
+
 void SavedNetworks::forget(const std::string& ssid) {
    for (auto it = networks_.begin(); it != networks_.end(); ++it) {
        if (it->ssid == ssid) {
@@ -60,6 +81,7 @@ void SavedNetworks::save() {
        store_.putString(key(i, "ssid").c_str(), networks_[i].ssid);
        store_.putString(key(i, "pass").c_str(), networks_[i].password);
        store_.putInt(key(i, "hid").c_str(), networks_[i].hidden ? 1 : 0);
+        store_.putString(key(i, "ip").c_str(), networks_[i].fixed ? net::formatFixed(networks_[i].ip) : "");
    }
    store_.putInt("net_count", count());
 }
@@ -3,6 +3,7 @@
 #include <string>
 #include <vector>

+#include "ipv4.h"
 #include "key_value_store.h"

 namespace roro {
@@ -11,6 +12,8 @@ struct SavedNetwork {
    std::string ssid;
    std::string password;  // empty for an open network
    bool hidden = false;   // doesn't broadcast its name, so never shows up in scans
+    bool fixed = false;    // S1, Q105: Fixed address (`ip`), or Automatic (DHCP)
+    net::FixedIp ip;
 };

 // The Saved Networks the Wi-Fi Service may join (see CONTEXT.md), persisted in internal flash.
@@ -28,6 +31,8 @@ class SavedNetworks {
    // Adds, or updates the password of an existing SSID. Empty on success, otherwise why not.
    std::string add(const std::string& ssid, const std::string& password, bool hidden = false);
    void forget(const std::string& ssid);
+    // The IP setting: Fixed with these values, or Automatic (DHCP) for nullptr. Empty, or why not.
+    std::string setIp(const std::string& ssid, const net::FixedIp* fixed);

   private:
    void save();
@@ -1,5 +1,6 @@
 #include "wifi_settings_page.h"

+#include "ipv4.h"
 #include "ui/fonts.h"
 #include "ui/widgets.h"

@@ -15,6 +16,62 @@ void WifiSettingsPage::enter() {

 void WifiSettingsPage::refreshMain() { main_.setCount(kFixedRows + saved_.count()); }

+// With Automatic, a network's page shows only the IP row and Forget.
+WifiSettingsPage::NetworkRow WifiSettingsPage::networkRow(int i) const {
+    if (draftFixed_) return static_cast<NetworkRow>(i);
+    return i == 0 ? kIpMode : kForget;
+}
+
+void WifiSettingsPage::openNetwork(const SavedNetwork& n) {
+    netSsid_ = n.ssid;
+    draftFixed_ = n.fixed;
+    draftAddress_ = n.fixed ? net::formatIpv4(n.ip.address) : "";
+    draftPrefix_ = n.fixed ? std::to_string(n.ip.prefix) : "";
+    draftGateway_ = n.fixed && n.ip.gateway ? net::formatIpv4(n.ip.gateway) : "";
+    network_.setCount(draftFixed_ ? 5 : 2);
+    network_.select(0);
+    view_ = View::Network;
+}
+
+// Leaving a network's page applies its IP setting (Q114), if it passes the checks (Q111).
+bool WifiSettingsPage::leaveNetwork() {
+    const SavedNetwork* n = saved_.find(netSsid_);
+    if (!n) return true;  // forgotten meanwhile
+    std::string why;
+    if (draftFixed_) {
+        net::FixedIp fixed;
+        why = net::parseFixed(draftAddress_ + "/" + draftPrefix_ + (draftGateway_.empty() ? "" : " " + draftGateway_), fixed);
+        if (draftAddress_.empty()) why = "A Fixed setting needs an address";
+        if (!why.empty()) {
+            warn(why);
+            return false;
+        }
+        bool same = n->fixed && n->ip.address == fixed.address && n->ip.prefix == fixed.prefix && n->ip.gateway == fixed.gateway;
+        if (same) return true;
+        why = saved_.setIp(netSsid_, &fixed);
+        if (why.empty()) warn(netSsid_ + ": fixed, " + net::formatFixed(fixed), NotificationLevel::Info);
+    } else {
+        if (!n->fixed) return true;
+        why = saved_.setIp(netSsid_, nullptr);
+        if (why.empty()) warn(netSsid_ + ": automatic (DHCP)", NotificationLevel::Info);
+    }
+    if (!why.empty()) {
+        warn(why);
+        return false;
+    }
+    wifi_.ipSettingChanged(netSsid_);
+    return true;
+}
+
+void WifiSettingsPage::edit(Field field, const std::string& title, const std::string& value, View from) {
+    field_ = field;
+    editTitle_ = title;
+    editFrom_ = from;
+    editor_ = LineEditor(field == Field::Ntp1 || field == Field::Ntp2 ? 63 : 15);
+    for (char ch : value) editor_.insert(static_cast<uint8_t>(ch));
+    view_ = View::Edit;
+}
+
 void WifiSettingsPage::warn(const std::string& text, NotificationLevel level) {
    bus_.publish(Event::withText(EventType::Notification, text.c_str(), static_cast<int32_t>(level)));
 }
@@ -35,42 +92,22 @@ bool WifiSettingsPage::onKey(const KeyEvent& e) {
    if (forgetDialog_) {
        forgetDialog_->onKey(e);
        if (forgetDialog_->result() == 1) {
-            saved_.forget(saved_.at(main_.selected() - kFixedRows).ssid);
-            refreshMain();
+            saved_.forget(netSsid_);
+            wifi_.ipSettingChanged(netSsid_);  // it may be the one in use
+            enter();
        }
-        if (forgetDialog_->result() != DialogModel::kPending) forgetDialog_.reset();
+        if (forgetDialog_ && forgetDialog_->result() != DialogModel::kPending) forgetDialog_.reset();
        return true;
    }

    switch (view_) {
-        case View::Main:
-            switch (e.key) {
-                case Key::Up: main_.up(); return true;
-                case Key::Down: main_.down(); return true;
-                case Key::Back: return false;
-                case Key::Left:
-                case Key::Right:
-                    if (main_.selected() != kToggle) return true;
-                    [[fallthrough]];
-                case Key::Select:
-                    switch (main_.selected()) {
-                        case kToggle: settings_.setBool(Setting::WifiEnabled, !settings_.getBool(Setting::WifiEnabled)); break;
-                        case kStatus: break;
-                        case kAddScanned:
-                            wifi_.startListScan();
-                            scan_.setCount(0);
-                            view_ = View::Scan;
-                            break;
-                        case kAddHidden:
-                            newHidden_ = true;
-                            editor_ = LineEditor(32);
-                            view_ = View::Ssid;
-                            break;
-                        default: forgetDialog_.reset(new DialogModel({"Cancel", "Forget"})); break;
-                    }
-                    return true;
-                default: return true;
-            }
+        case View::Main: return mainKey(e);
+        case View::Servers: return serversKey(e);
+        case View::Network: return networkKey(e);
+        case View::Edit: return editKey(e);
+        case View::Details:
+            if (e.key == Key::Back || e.key == Key::Select) view_ = View::Main;
+            return true;

        case View::Scan: {
            std::vector<ScanEntry> found;
@@ -131,6 +168,159 @@ bool WifiSettingsPage::onKey(const KeyEvent& e) {
    return true;
 }

+bool WifiSettingsPage::mainKey(const KeyEvent& e) {
+    switch (e.key) {
+        case Key::Up: main_.up(); return true;
+        case Key::Down: main_.down(); return true;
+        case Key::Back: return false;
+        case Key::Left:
+        case Key::Right:
+            if (main_.selected() != kToggle) return true;
+            [[fallthrough]];
+        case Key::Select:
+            switch (main_.selected()) {
+                case kToggle: settings_.setBool(Setting::WifiEnabled, !settings_.getBool(Setting::WifiEnabled)); break;
+                case kStatus: view_ = View::Details; break;
+                case kServers:
+                    servers_.setCount(kServerRows);
+                    view_ = View::Servers;
+                    break;
+                case kAddScanned:
+                    wifi_.startListScan();
+                    scan_.setCount(0);
+                    view_ = View::Scan;
+                    break;
+                case kAddHidden:
+                    newHidden_ = true;
+                    editor_ = LineEditor(32);
+                    view_ = View::Ssid;
+                    break;
+                default: openNetwork(saved_.at(main_.selected() - kFixedRows)); break;
+            }
+            return true;
+        default: return true;
+    }
+}
+
+// DNS and NTP servers (Q108 to Q110).
+bool WifiSettingsPage::serversKey(const KeyEvent& e) {
+    switch (e.key) {
+        case Key::Up: servers_.up(); break;
+        case Key::Down: servers_.down(); break;
+        case Key::Back: view_ = View::Main; break;
+        case Key::Left:
+        case Key::Right:
+            if (servers_.selected() != kDnsAlways) break;
+            [[fallthrough]];
+        case Key::Select:
+            switch (servers_.selected()) {
+                case kDns1: edit(Field::Dns1, "First DNS server", settings_.getString(Setting::Dns1), View::Servers); break;
+                case kDns2: edit(Field::Dns2, "Second DNS server (or empty)", settings_.getString(Setting::Dns2), View::Servers); break;
+                case kDnsAlways:
+                    settings_.setBool(Setting::DnsAlways, !settings_.getBool(Setting::DnsAlways));
+                    wifi_.serversChanged();
+                    break;
+                case kNtp1: edit(Field::Ntp1, "First NTP server", settings_.getString(Setting::Ntp1), View::Servers); break;
+                case kNtp2: edit(Field::Ntp2, "Second NTP server (or empty)", settings_.getString(Setting::Ntp2), View::Servers); break;
+            }
+            break;
+        default: break;
+    }
+    return true;
+}
+
+bool WifiSettingsPage::networkKey(const KeyEvent& e) {
+    switch (e.key) {
+        case Key::Up: network_.up(); break;
+        case Key::Down: network_.down(); break;
+        case Key::Back:
+            if (leaveNetwork()) enter();
+            break;
+        case Key::Left:
+        case Key::Right:
+            if (networkRow(network_.selected()) != kIpMode) break;
+            [[fallthrough]];
+        case Key::Select:
+            switch (networkRow(network_.selected())) {
+                case kIpMode: {
+                    draftFixed_ = !draftFixed_;
+                    // Fixed for the first time: start from what the network gave us, if we're on it.
+                    WifiService::Connection now = wifi_.connection();
+                    if (draftFixed_ && draftAddress_.empty() && now.connected && wifi_.ssid() == netSsid_) {
+                        draftAddress_ = now.address;
+                        draftPrefix_ = std::to_string(now.prefix);
+                        draftGateway_ = now.gateway;
+                    }
+                    if (draftFixed_ && draftPrefix_.empty()) draftPrefix_ = "24";
+                    network_.setCount(draftFixed_ ? 5 : 2);
+                    network_.select(0);
+                    break;
+                }
+                case kAddress: edit(Field::Address, "Address", draftAddress_, View::Network); break;
+                case kPrefix: edit(Field::Prefix, "Prefix (1 to 30; 24 = 255.255.255.0)", draftPrefix_, View::Network); break;
+                case kGateway: edit(Field::Gateway, "Gateway (or empty for none)", draftGateway_, View::Network); break;
+                case kForget: forgetDialog_.reset(new DialogModel({"Cancel", "Forget"})); break;
+            }
+            break;
+        default: break;
+    }
+    return true;
+}
+
+// One field. Addresses take digits and dots only (Q112); what's typed is checked on Enter (Q111).
+bool WifiSettingsPage::editKey(const KeyEvent& e) {
+    bool name = field_ == Field::Ntp1 || field_ == Field::Ntp2;
+    switch (e.key) {
+        case Key::Char: {
+            bool digit = e.ch >= '0' && e.ch <= '9';
+            bool ok = name ? e.ch > ' ' && e.ch < 0x7F : field_ == Field::Prefix ? digit : digit || e.ch == '.';
+            if (ok) editor_.insert(e.ch);
+            break;
+        }
+        case Key::Delete: editor_.backspace(); break;
+        case Key::Left: editor_.left(); break;
+        case Key::Right: editor_.right(); break;
+        case Key::Back: view_ = editFrom_; break;
+        case Key::Select: {
+            std::string text = editor_.text(), why;
+            uint32_t address;
+            switch (field_) {
+                case Field::Address:
+                    if (!net::parseIpv4(text, address)) why = "Four numbers from 0 to 255, like 10.39.39.13";
+                    else draftAddress_ = text;
+                    break;
+                case Field::Prefix: {
+                    int p = text.empty() ? 0 : atoi(text.c_str());
+                    if (p < 1 || p > 30) why = "The prefix must be 1 to 30";
+                    else draftPrefix_ = std::to_string(p);
+                    break;
+                }
+                case Field::Gateway:
+                    if (!text.empty() && !net::parseIpv4(text, address)) why = "Four numbers from 0 to 255, or empty";
+                    else draftGateway_ = text;
+                    break;
+                case Field::Dns1:
+                case Field::Dns2:
+                    if (!settings_.setString(field_ == Field::Dns1 ? Setting::Dns1 : Setting::Dns2, text))
+                        why = field_ == Field::Dns1 ? "An IPv4 address, like 9.9.9.9" : "An IPv4 address, or empty";
+                    else wifi_.serversChanged();
+                    break;
+                case Field::Ntp1:
+                case Field::Ntp2:
+                    if (!settings_.setString(field_ == Field::Ntp1 ? Setting::Ntp1 : Setting::Ntp2, text))
+                        why = field_ == Field::Ntp1 ? "A host name or an IPv4 address" : "A host name, an IPv4 address, or empty";
+                    else wifi_.serversChanged();
+                    break;
+            }
+            if (why.empty()) view_ = editFrom_;
+            else warn(why);
+            break;
+        }
+        default: break;
+    }
+    return true;
+}
+
 void WifiSettingsPage::draw(Canvas& c) {
    const auto& area = theme::kContent;
    switch (view_) {
@@ -141,6 +331,7 @@ void WifiSettingsPage::draw(Canvas& c) {
                    switch (i) {
                        case kToggle: return "Wi-Fi";
                        case kStatus: return "Status";
+                        case kServers: return "DNS and NTP";
                        case kAddScanned: return "Add a network";
                        case kAddHidden: return "Add a hidden network";
                        default: {
@@ -153,14 +344,78 @@ void WifiSettingsPage::draw(Canvas& c) {
                    switch (i) {
                        case kToggle: return settings_.getBool(Setting::WifiEnabled) ? "On" : "Off";
                        case kStatus: return statusText();
+                        case kServers:
                        case kAddScanned:
                        case kAddHidden: return ">";
+                        default: return saved_.at(i - kFixedRows).fixed ? "fixed" : "";
+                    }
+                });
+            break;
+
+        case View::Details: drawDetails(c); break;
+
+        case View::Servers:
+            widgets::list(
+                c, servers_, area,
+                [](int i) -> std::string {
+                    switch (i) {
+                        case kDns1: return "DNS 1";
+                        case kDns2: return "DNS 2";
+                        case kDnsAlways: return "Always use my DNS";
+                        case kNtp1: return "NTP 1";
+                        default: return "NTP 2";
+                    }
+                },
+                [this](int i) -> std::string {
+                    switch (i) {
+                        case kDns1: return settings_.getString(Setting::Dns1);
+                        case kDns2: return settings_.getString(Setting::Dns2).empty() ? "none" : settings_.getString(Setting::Dns2);
+                        case kDnsAlways: return settings_.getBool(Setting::DnsAlways) ? "On" : "Off";
+                        case kNtp1: return settings_.getString(Setting::Ntp1);
+                        default: return settings_.getString(Setting::Ntp2).empty() ? "none" : settings_.getString(Setting::Ntp2);
+                    }
+                });
+            break;
+
+        case View::Network: {
+            c.setFont(&fonts::small);
+            c.setTextColor(theme::kMuted);
+            c.drawString(netSsid_.c_str(), 4, area.y + 2);
+            widgets::list(
+                c, network_, {area.x, area.y + 12, area.w, area.h - 12},
+                [this](int i) -> std::string {
+                    switch (networkRow(i)) {
+                        case kIpMode: return "IP address";
+                        case kAddress: return "  Address";
+                        case kPrefix: return "  Prefix";
+                        case kGateway: return "  Gateway";
+                        default: return "Forget this network";
+                    }
+                },
+                [this](int i) -> std::string {
+                    switch (networkRow(i)) {
+                        case kIpMode: return draftFixed_ ? "Fixed" : "Automatic";
+                        case kAddress: return draftAddress_.empty() ? "not set" : draftAddress_;
+                        case kPrefix: {
+                            int p = atoi(draftPrefix_.c_str());
+                            return draftPrefix_ + " (" + net::formatIpv4(net::maskOf(p)) + ")";
+                        }
+                        case kGateway: return draftGateway_.empty() ? "none" : draftGateway_;
                        default: return "";
                    }
                });
-            if (forgetDialog_ && main_.selected() >= kFixedRows)
-                widgets::dialog(c, "Forget network?", saved_.at(main_.selected() - kFixedRows).ssid, *forgetDialog_);
+            if (forgetDialog_) widgets::dialog(c, "Forget network?", netSsid_, *forgetDialog_);
            break;
+        }
+
+        case View::Edit: {
+            c.setFont(&fonts::body);
+            c.setTextColor(theme::kMuted);
+            c.drawString(editTitle_.c_str(), 4, area.y + 4);
+            widgets::lineEditor(c, editor_, {4, area.y + 22, area.w - 8, 0});
+            c.drawString("Enter: save   `: cancel", 4, area.y + 44);
+            break;
+        }

        case View::Scan: {
            if (!wifi_.listScanDone()) {
@@ -195,4 +450,25 @@ void WifiSettingsPage::draw(Canvas& c) {
    }
 }

+// What the device is using and where each part came from (Q113).
+void WifiSettingsPage::drawDetails(Canvas& c) {
+    const auto& area = theme::kContent;
+    WifiService::Connection n = wifi_.connection();
+    std::vector<std::string> lines;
+    if (!n.connected) {
+        lines = {statusText(), "", "`: back"};
+    } else {
+        lines.push_back(wifi_.ssid() + ", " + std::to_string(wifi_.rssi()) + " dBm");
+        lines.push_back("Address " + n.address + "/" + std::to_string(n.prefix) + (n.fixed ? " (fixed)" : " (DHCP)"));
+        lines.push_back("Mask " + n.mask);
+        lines.push_back("Gateway " + (n.gateway.empty() ? std::string("none") : n.gateway));
+        std::string from = n.dnsFromSettings ? " (Settings)" : " (DHCP)";
+        lines.push_back("DNS " + (n.dns[0].empty() ? std::string("none") : n.dns[0] + from));
+        if (!n.dns[1].empty()) lines.push_back("DNS " + n.dns[1] + from);
+        for (int i = 0; i < n.ntpCount; i++)
+            lines.push_back("NTP " + n.ntp[i].server + (n.ntp[i].fromDhcp ? " (DHCP)" : "") + (n.ntp[i].answered ? ", answered" : ""));
+    }
+    widgets::textLines(c, lines, 0, {area.x + 2, area.y + 2, area.w - 2, area.h - 2});
+}
+
 }  // namespace roro
@@ -16,8 +16,9 @@

 namespace roro {

-// Settings → Wi-Fi: the On/Off switch, current connection, Saved Networks, and adding networks
-// from a scan or by name (hidden). Owned by the Settings App.
+// Settings → Wi-Fi: the On/Off switch, the connection and its details, DNS and NTP servers, and
+// the Saved Networks: adding one from a scan or by name (hidden), and each one's own page with its
+// IP setting, Automatic or Fixed (docs/milestones/S1.md, Q113). Owned by the Settings App.
 class WifiSettingsPage {
   public:
    WifiSettingsPage(Settings& settings, SavedNetworks& saved, WifiService& wifi, EventBus& bus)
@@ -25,17 +26,31 @@ class WifiSettingsPage {

    void enter();
    bool onKey(const KeyEvent& e);  // false: leave the page
-    bool textEntryActive() const { return view_ == View::Ssid || view_ == View::Password; }
-    bool live() const { return view_ == View::Main || view_ == View::Scan; }  // redraw periodically
+    bool textEntryActive() const { return view_ == View::Ssid || view_ == View::Password || view_ == View::Edit; }
+    // Redraw periodically: the status, a scan, the connection details.
+    bool live() const { return view_ == View::Main || view_ == View::Scan || view_ == View::Details; }
    void draw(Canvas& c);

   private:
-    enum class View { Main, Scan, Ssid, Password };
-    enum Fixed { kToggle, kStatus, kAddScanned, kAddHidden, kFixedRows };
+    enum class View { Main, Scan, Ssid, Password, Details, Servers, Network, Edit };
+    enum Fixed { kToggle, kStatus, kServers, kAddScanned, kAddHidden, kFixedRows };
+    enum ServerRow { kDns1, kDns2, kDnsAlways, kNtp1, kNtp2, kServerRows };
+    // A Saved Network's page: with Automatic, only kIpMode and kForget are shown.
+    enum NetworkRow { kIpMode, kAddress, kPrefix, kGateway, kForget };
+    enum class Field { Address, Prefix, Gateway, Dns1, Dns2, Ntp1, Ntp2 };

    void refreshMain();
    void warn(const std::string& text, NotificationLevel level = NotificationLevel::Warning);
    std::string statusText() const;
+    bool mainKey(const KeyEvent& e);
+    bool serversKey(const KeyEvent& e);
+    bool networkKey(const KeyEvent& e);
+    bool editKey(const KeyEvent& e);
+    void openNetwork(const SavedNetwork& n);
+    bool leaveNetwork();  // checks and applies the draft; false (with a Toast) when it's refused
+    NetworkRow networkRow(int i) const;
+    void edit(Field field, const std::string& title, const std::string& value, View from);
+    void drawDetails(Canvas& c);

    Settings& settings_;
    SavedNetworks& saved_;
@@ -44,10 +59,21 @@ class WifiSettingsPage {
    View view_ = View::Main;
    ListModel main_{theme::kContent.h / theme::kLineHeight};
    ListModel scan_{theme::kContent.h / theme::kLineHeight};
+    ListModel servers_{theme::kContent.h / theme::kLineHeight};
+    ListModel network_{theme::kContent.h / theme::kLineHeight - 1};
    LineEditor editor_{63};
    std::string newSsid_;
    bool newHidden_ = false;
    std::unique_ptr<DialogModel> forgetDialog_;
+    // The Saved Network whose page is open, and its IP setting as being typed (a draft: applied on
+    // leaving the page, so a half-typed address is never used).
+    std::string netSsid_;
+    bool draftFixed_ = false;
+    std::string draftAddress_, draftPrefix_, draftGateway_;
+    // The field being edited, and where Enter and Back return to.
+    Field field_ = Field::Address;
+    std::string editTitle_;
+    View editFrom_ = View::Main;
 };

 }  // namespace roro
@@ -18,11 +18,14 @@
 #include "apps/setup_app.h"
 #include "event_bus.h"
 #include "file_receiver.h"
+#include "ipv4.h"
 #include "key_mapper.h"
 #include "platform/console.h"
 #include "platform/crash_report.h"
 #include "platform/nvs_store.h"
 #include "platform/system_info.h"
+#include "sd_card_id.h"
+#include "sd_fault.h"
 #include "service_manager.h"
 #include "platform/identity.h"
 #include "services/battery_service.h"
@@ -357,6 +360,27 @@ static void uploadStep() {
    }
 }

+#ifdef RORO_DEBUG
+// `wifi ip ... try <seconds>`: a trial IP setting that reverts unless `wifi ip keep` arrives, so a
+// wrong address tried over Wi-Fi doesn't cut the device off for good.
+static struct {
+    bool active = false;
+    uint32_t untilMs = 0;
+    std::string ssid;
+    bool wasFixed = false;
+    net::FixedIp was;
+} ipTrial;
+
+static void ipTrialStep() {
+    if (!ipTrial.active || static_cast<int32_t>(millis() - ipTrial.untilMs) < 0) return;
+    ipTrial.active = false;
+    savedNetworks->setIp(ipTrial.ssid, ipTrial.wasFixed ? &ipTrial.was : nullptr);
+    console.printf("wifi ip: trial over, %s is back to %s\n", ipTrial.ssid.c_str(),
+                   ipTrial.wasFixed ? net::formatFixed(ipTrial.was).c_str() : "Automatic (DHCP)");
+    wifi->ipSettingChanged(ipTrial.ssid);
+}
+#endif
+
 static const char* const kHelp =
    "info              firmware, uptime, memory, Wi-Fi, app slots\n"
    "tasks             FreeRTOS tasks: state, priority, free stack, CPU\n"
@@ -372,12 +396,15 @@ static const char* const kHelp =
    "coredump erase    forget the core dump in flash\n"
    "key <name|char>   press a key: up down left right select back home del tab space, or one character\n"
    "wifi status | wifi add <ssid><TAB><password>\n"
+    "wifi ip <ssid> dhcp | wifi ip <ssid> <address>/<prefix> [gateway]   a Saved Network's IP setting\n"
+    "wifi dns <a> [b] | wifi dns always on|off | wifi ntp <a> [b]   DNS and NTP servers\n"
    "gemini get <url>  fetch a Gemini page and report header, size, certificate, heap\n"
    "irc start | irc stop | irc dump | irc say <buffer> <text>\n"
    "ls [folder] | rm <path> | install <path.ota> (Update from SD)\n"
-    "sd list | cat <path> | log <text> | burst | sound on|off | short | normal\n"
+    "sd card | sd list | cat <path> | log <text> | burst | sound on|off | short | normal\n"
 #ifdef RORO_DEBUG
    "crash abort|wdt   crash on purpose (to test crash reports and Safe Mode)\n"
+    "wifi ip ... try <seconds> | wifi ip keep   a trial IP setting: back to the previous one unless kept\n"
    "lora inject <hex> [rssi] [snr]   a packet into the LoRa Scanner as if received (nothing is sent)\n"
    "coredump get      (Debug Console only) send the raw core dump: use scripts/rdbg.py coredump\n"
    "reset             (Debug Console only) restart at once, even if the main loop is stuck\n"
@@ -400,8 +427,8 @@ static void runCommand(String line) {
    if (line == "help") console.print(kHelp);
    if (line == "info") {
        system_info::printSystem(console);
-        console.printf("wifi: %s, ip %s, rssi %d | sd: %s\n", wifi->ssid().c_str(), wifi->ip().c_str(), wifi->rssi(),
-                       storageService->state().present ? "present" : "none");
+        console.printf("wifi: %s, ip %s, rssi %d | sd: %s, %u write faults\n", wifi->ssid().c_str(), wifi->ip().c_str(),
+                       wifi->rssi(), storageService->state().present ? "present" : "none", (unsigned)sdLastFault().count);
        console.printf("update: %s\n", update->onProbation() ? "on probation" : "confirmed");
        system_info::printSlots(console, nvs);
    }
@@ -537,6 +564,18 @@ static void runCommand(String line) {
        }
    }
    if (line.startsWith("sd put ")) startUpload(line.substring(7));  // then raw bytes: see uploadStep()
+    if (line == "sd card") {  // what the card says it is, from its CID register
+        if (!storageService->state().present) return (void)console.println("sd card: no card");
+        storageService->runJob([]() {
+            uint8_t cid[16];
+            const char* type = SD.cardType() == CARD_SDHC ? "SDHC/SDXC" : SD.cardType() == CARD_SD ? "SDSC" : "MMC or unknown";
+            if (!sdReadCid(cid)) return (void)console.println("sd card: the card didn't answer");
+            console.printf("sd card: %s, %.1f GB, %s\n", type, SD.cardSize() / 1e9, sdCardSummary(parseSdCid(cid)).c_str());
+            console.printf("sd card: CID");
+            for (uint8_t b : cid) console.printf(" %02x", b);
+            console.println();
+        });
+    }
    if (line == "sd list") {
        storageService->requestListing();
        listingWanted = true;
@@ -574,11 +613,77 @@ static void runCommand(String line) {
            }
        });
    }
-    if (line == "wifi status")
+    if (line == "wifi status") {
        console.printf("wifi: state %d ssid '%s' rssi %d ip %s clock %s heap %u min %u | fw %s%s\n",
                       (int)wifi->state(), wifi->ssid().c_str(), wifi->rssi(), wifi->ip().c_str(),
                       clockService->displayTime().c_str(), ESP.getFreeHeap(), ESP.getMinFreeHeap(), versionString(),
                       update->onProbation() ? " (on probation)" : "");
+        WifiService::Connection c = wifi->connection();  // S1, Q115: what's in use and where it came from
+        if (c.connected) {
+            console.printf("wifi: address %s/%d (%s), gateway %s\n", c.address.c_str(), c.prefix, c.fixed ? "fixed" : "DHCP",
+                           c.gateway.empty() ? "none" : c.gateway.c_str());
+            console.printf("wifi: dns %s %s (%s)\n", c.dns[0].empty() ? "none" : c.dns[0].c_str(), c.dns[1].c_str(),
+                           c.dnsFromSettings ? "Settings" : "DHCP");
+            console.print("wifi: ntp");
+            for (int i = 0; i < c.ntpCount; i++) console.printf(" %s (%s%s)", c.ntp[i].server.c_str(), c.ntp[i].fromDhcp ? "DHCP" : "Settings", c.ntp[i].answered ? ", answered" : "");
+            console.println(c.ntpCount ? "" : " none");
+        }
+    }
+    if (line.startsWith("wifi ip ")) {  // wifi ip <ssid> dhcp | <address>/<prefix> [gateway]  (the SSID may hold spaces)
+        std::string rest = line.substring(8).c_str();
+#ifdef RORO_DEBUG
+        if (rest == "keep") {  // the trial setting stays
+            console.println(ipTrial.active ? "wifi ip: kept" : "wifi ip: no trial running");
+            ipTrial.active = false;
+            return;
+        }
+        uint32_t trialS = 0;
+        size_t tryAt = rest.rfind(" try ");
+        if (tryAt != std::string::npos) {
+            trialS = strtoul(rest.c_str() + tryAt + 5, nullptr, 10);
+            rest = rest.substr(0, tryAt);
+        }
+#endif
+        std::string ssid, why;
+        net::FixedIp fixed;
+        bool dhcp = rest.size() > 5 && rest.compare(rest.size() - 5, 5, " dhcp") == 0;
+        if (dhcp) ssid = rest.substr(0, rest.size() - 5);
+        else {
+            size_t slash = rest.rfind('/'), space = slash == std::string::npos ? slash : rest.rfind(' ', slash);
+            if (space == std::string::npos) why = "usage: wifi ip <ssid> dhcp | <address>/<prefix> [gateway]";
+            else {
+                ssid = rest.substr(0, space);
+                why = net::parseFixed(rest.substr(space + 1), fixed);
+            }
+        }
+        const SavedNetwork* before = why.empty() ? savedNetworks->find(ssid) : nullptr;
+#ifdef RORO_DEBUG
+        if (before && trialS) ipTrial = {true, millis() + trialS * 1000, ssid, before->fixed, before->ip};
+#endif
+        if (why.empty()) why = savedNetworks->setIp(ssid, dhcp ? nullptr : &fixed);
+        if (!why.empty()) return (void)console.printf("wifi ip: %s\n", why.c_str());
+        console.printf("wifi ip: %s is now %s\n", ssid.c_str(), dhcp ? "Automatic (DHCP)" : net::formatFixed(fixed).c_str());
+        wifi->ipSettingChanged(ssid);
+    }
+    if ((line.startsWith("wifi dns ") && !line.startsWith("wifi dns always")) || line.startsWith("wifi ntp ")) {  // <a> [b]
+        bool dns = line.startsWith("wifi dns ");
+        std::string rest = line.substring(9).c_str();
+        size_t space = rest.find(' ');
+        std::string first = rest.substr(0, space), second = space == std::string::npos ? "" : rest.substr(space + 1);
+        Setting a = dns ? Setting::Dns1 : Setting::Ntp1, b = dns ? Setting::Dns2 : Setting::Ntp2;
+        std::string oldFirst = settings.getString(a);
+        // Both or neither: a refused second entry leaves the first as it was.
+        bool ok = settings.setString(a, first) && (settings.setString(b, second) || (settings.setString(a, oldFirst), false));
+        if (!ok) console.printf("wifi %s: %s\n", dns ? "dns" : "ntp", dns ? "an IPv4 address, then a second one if you like" : "a host name or an IPv4 address, then a second one if you like");
+        else {
+            console.printf("wifi %s: %s %s\n", dns ? "dns" : "ntp", first.c_str(), second.c_str());
+            wifi->serversChanged();
+        }
+    }
+    if (line == "wifi dns always on" || line == "wifi dns always off") {
+        settings.setBool(Setting::DnsAlways, line.endsWith("on"));
+        wifi->serversChanged();
+    }
    if (line == "sound off") settings.setBool(Setting::Sound, false);
    if (line == "sound on") settings.setBool(Setting::Sound, true);
    if (line == "short") {
@@ -657,6 +762,9 @@ void loop() {

    serialCommands();
    remoteCommands();
+#ifdef RORO_DEBUG
+    ipTrialStep();
+#endif
    noteStableOnce(now);
    uploadStep();
    printListingWhenReady();
@@ -17,6 +17,7 @@
 #include "file_receiver.h"
 #include "sha256.h"
 #include "platform/console.h"
+#include "sd_fault.h"
 #include "version.h"

 namespace roro {
@@ -232,7 +233,16 @@ void DebugConsole::put(NetworkClient& client, const std::string& args) {
        while (r.state() == S::Receiving || r.state() == S::Writing) {
            if (r.state() == S::Writing) {
                const auto& c = r.chunk();
+                uint32_t t0 = millis();
                bool ok = f.write(c.data(), c.size()) == c.size();
+                uint32_t took = millis() - t0;
+                // Why, from our copy of the SD driver (lib/SD, #21): the step that gave up and what
+                // the card answered. How long it took tells a 500 ms busy timeout from a refusal.
+                if (!ok) {
+                    SdFault sd = sdLastFault();
+                    console.printf("put: write failed at %u after %u ms: SD step %u, answer 0x%02X, status 0x%04X (%u so far)\n",
+                                   (unsigned)r.received(), (unsigned)took, sd.step, sd.token, (unsigned)sd.resp, (unsigned)sd.count);
+                }
                // A card can fail one write and take the next. FATFS keeps a failed file in error,
                // so: close, cut back to the last good byte, reopen, try again. Earlier chunks may
                // have been lost with the write buffer (M3: 3 KB came back as zeros): never extend
@@ -166,7 +166,7 @@ void StorageService::format() {
    mounted_ = false;

    bool ok = false;
-    uint8_t pdrv = sdcard_init(pins::kSdCs, &sharedSpi(), 20000000);
+    uint8_t pdrv = sdcard_init(pins::kSdCs, &sharedSpi(), kSdHz);
    if (pdrv != 0xFF) {
        constexpr size_t kWorkSize = 4096;  // FF_MAX_SS
        std::unique_ptr<uint8_t[]> work(new uint8_t[kWorkSize]);
@@ -182,7 +182,7 @@ void StorageService::format() {
 }

 bool StorageService::mount() {
-    return SD.begin(pins::kSdCs, sharedSpi(), 20000000, "/sd", 5, false);
+    return SD.begin(pins::kSdCs, sharedSpi(), kSdHz, "/sd", 5, false);
 }

 void StorageService::poll() {
@@ -56,6 +56,7 @@ class StorageService : public Service {
    static constexpr uint32_t kWakeMs = 1000;
    static constexpr uint32_t kPollEvery = 15;  // wake-ups between usage checks
    static constexpr size_t kMaxPendingBytes = 16 * 1024;
+    static constexpr uint32_t kSdHz = 20000000;  // the card's SPI clock; 10 MHz changed nothing (ADR 0007)

    static void taskEntry(void* self);
    void loop();
@@ -3,10 +3,121 @@
 #include <WiFi.h>
 #include <esp_sntp.h>
 #include <esp_wifi.h>
+#include <lwip/ip_addr.h>
+
+#include <cstring>
+
+#include "ipv4.h"

 namespace roro {


+namespace {
+IPAddress toIp(uint32_t a) { return IPAddress(a >> 24, a >> 16 & 255, a >> 8 & 255, a & 255); }
+IPAddress toIp(const std::string& text) {
+    uint32_t a = 0;
+    net::parseIpv4(text, a);
+    return toIp(a);
+}
+const IPAddress kNoAddress(static_cast<uint32_t>(0));
+// A slot lwIP filled from DHCP has an address and no name; ours are set by name.
+bool sntpSlotFromDhcp(int i) {
+    const ip_addr_t* a = esp_sntp_getserver(i);
+    return !esp_sntp_getservername(i) && a && !ip_addr_isany(a);
+}
+constexpr int kNtpSlots = 3;  // CONFIG_LWIP_SNTP_MAX_SERVERS
+constexpr uint32_t kServersEveryMs = 30000;
+}  // namespace
+
+// Joins a Saved Network with its IP setting (S1, Q105): Fixed, or DHCP.
+void WifiService::join(const std::string& ssid, const std::string& password) {
+    const SavedNetwork* n = saved_.find(ssid);
+    fixed_ = n && n->fixed;
+    if (fixed_) {
+        // Nothing comes from DHCP here: forget the NTP servers a previous network offered.
+        for (int i = 0; i < kNtpSlots; i++)
+            if (sntpSlotFromDhcp(i)) esp_sntp_setserver(i, nullptr);
+        WiFi.config(toIp(n->ip.address), toIp(n->ip.gateway), toIp(net::maskOf(n->ip.prefix)),
+                    toIp(settings_.getString(Setting::Dns1)), toIp(settings_.getString(Setting::Dns2)));
+    } else {
+        WiFi.config(kNoAddress, kNoAddress, kNoAddress);  // DHCP
+    }
+    WiFi.begin(ssid.c_str(), password.empty() ? nullptr : password.c_str());
+}
+
+void WifiService::ipSettingChanged(const std::string& ssid) {
+    if (controller_.state() != WifiController::State::Connected || controller_.ssid() != ssid) return;
+    WiFi.disconnect();
+    apply(controller_.disconnected(millis()));
+    controller_.retryNow(millis());
+}
+
+// DNS and NTP as decided in Q108 and Q110. Run when connected, when a setting changes, and now
+// and then: a DHCP renewal puts DHCP's DNS back and clears the NTP slots it didn't fill.
+void WifiService::applyServers(Why why) {
+    if (controller_.state() != WifiController::State::Connected) return;
+    serversCheckedMs_ = millis();
+    bool changed = why != Why::Check;
+
+    bool wasFromSettings = dnsFromSettings_;
+    dnsFromSettings_ = fixed_ || settings_.getBool(Setting::DnsAlways);
+    if (dnsFromSettings_) {
+        IPAddress dns1 = toIp(settings_.getString(Setting::Dns1)), dns2 = toIp(settings_.getString(Setting::Dns2));
+        if (WiFi.dnsIP(0) != dns1 || WiFi.dnsIP(1) != dns2) WiFi.setDNS(dns1, dns2);
+    } else if (why == Why::SettingsChanged && wasFromSettings) {
+        // "Always use my DNS" was switched off: only a new lease brings DHCP's servers back.
+        ipSettingChanged(controller_.ssid());
+        return;
+    }
+
+    // NTP: the servers DHCP offered stay first; ours follow.
+    int fromDhcp = 0;
+    while (!fixed_ && fromDhcp < kNtpSlots && sntpSlotFromDhcp(fromDhcp)) fromDhcp++;
+    std::string wanted[2] = {settings_.getString(Setting::Ntp1), settings_.getString(Setting::Ntp2)};
+    bool touched = false;
+    for (int i = fromDhcp, mine = 0; i < kNtpSlots; i++, mine++) {
+        const char* current = esp_sntp_getservername(i);
+        if (mine < 2 && !wanted[mine].empty()) {
+            if (current && wanted[mine] == current) continue;
+            ntpNames_[mine] = wanted[mine];
+            esp_sntp_setservername(i, ntpNames_[mine].c_str());
+            touched = true;
+        } else if (current || sntpSlotFromDhcp(i)) {
+            esp_sntp_setserver(i, nullptr);
+            touched = true;
+        }
+    }
+    if (!esp_sntp_enabled()) {
+        esp_sntp_setoperatingmode(ESP_SNTP_OPMODE_POLL);
+        esp_sntp_init();
+    } else if (touched || changed) {
+        esp_sntp_restart();
+    }
+    if (touched || changed) ntpWaiting_ = true;
+}
+
+WifiService::Connection WifiService::connection() const {
+    Connection c;
+    c.connected = controller_.state() == WifiController::State::Connected;
+    if (!c.connected) return c;
+    c.fixed = fixed_;
+    c.dnsFromSettings = dnsFromSettings_;
+    c.address = WiFi.localIP().toString().c_str();
+    c.mask = WiFi.subnetMask().toString().c_str();
+    c.prefix = WiFi.subnetCIDR();
+    IPAddress gateway = WiFi.gatewayIP();
+    if (gateway != kNoAddress) c.gateway = gateway.toString().c_str();
+    for (int i = 0; i < 2; i++)
+        if (WiFi.dnsIP(i) != kNoAddress) c.dns[i] = WiFi.dnsIP(i).toString().c_str();
+    for (int i = 0; i < kNtpSlots; i++) {
+        const char* name = esp_sntp_getservername(i);
+        bool answered = esp_sntp_getreachability(i) != 0;
+        if (name) c.ntp[c.ntpCount++] = {name, false, answered};
+        else if (sntpSlotFromDhcp(i)) c.ntp[c.ntpCount++] = {ipaddr_ntoa(esp_sntp_getserver(i)), true, answered};
+    }
+    return c;
+}
+
 std::string WifiService::ip() const {
    return controller_.state() == WifiController::State::Connected ? WiFi.localIP().toString().c_str() : "";
 }
@@ -20,6 +131,7 @@ void WifiService::startScan(int channel) {
        WiFi.mode(WIFI_STA);
        WiFi.setAutoReconnect(false);  // the controller decides when to reconnect
        esp_wifi_set_country_code("EU", true);
+        esp_sntp_servermode_dhcp(true);  // before DHCP runs: take the NTP servers it offers (Q110)
        radioInitialised_ = true;
    }
    if (scanRunning_) return;
@@ -87,13 +199,7 @@ void WifiService::finishScan(uint32_t nowMs) {

 void WifiService::startNtp() {
    // Not configTime(): it would overwrite the POSIX TZ the Clock applies.
-    if (!esp_sntp_enabled()) {
-        esp_sntp_setoperatingmode(ESP_SNTP_OPMODE_POLL);
-        esp_sntp_setservername(0, "pool.ntp.org");
-        esp_sntp_init();
-    } else {
-        esp_sntp_restart();
-    }
+    applyServers(Why::Joined);
    ntpWaiting_ = true;
 }

@@ -102,7 +208,7 @@ void WifiService::apply(const WifiController::Step& step) {
    switch (step.action) {
        case Action::None: break;
        case Action::StartScan: startScan(); break;
-        case Action::Connect: WiFi.begin(step.ssid.c_str(), step.password.empty() ? nullptr : step.password.c_str()); break;
+        case Action::Connect: join(step.ssid, step.password); break;
        case Action::Disconnect: WiFi.disconnect(); break;
        case Action::RadioOff:
            WiFi.disconnect(true);
@@ -143,6 +249,8 @@ void WifiService::tick(uint32_t nowMs) {

    apply(controller_.update(nowMs, settings_.getBool(Setting::WifiEnabled)));

+    if (controller_.state() == State::Connected && nowMs - serversCheckedMs_ >= kServersEveryMs) applyServers(Why::Check);
+
    if (ntpWaiting_ && sntp_get_sync_status() == SNTP_SYNC_STATUS_COMPLETED) {
        ntpWaiting_ = false;
        clock_.set(static_cast<int64_t>(time(nullptr)), TimeSource::Ntp);
@@ -36,6 +36,27 @@ class WifiService : public Service {
    // Done with list scans: switch the radio back off if Wi-Fi itself is off.
    void endListScans();

+    // What the device is using and where each part came from (S1, Q113).
+    struct Connection {
+        bool connected = false;
+        bool fixed = false;            // the address: Fixed, or from DHCP
+        bool dnsFromSettings = false;  // DNS: from Settings, or from DHCP
+        std::string address, mask, gateway;
+        int prefix = 0;
+        std::string dns[2];
+        struct Ntp {
+            std::string server;
+            bool fromDhcp = false;
+            bool answered = false;  // it has replied since the last (re)start
+        } ntp[3];
+        int ntpCount = 0;
+    };
+    Connection connection() const;
+    // A Saved Network's IP setting changed: if it's the one in use, join it again with it (Q114).
+    void ipSettingChanged(const std::string& ssid);
+    // The DNS or NTP settings changed: use them now.
+    void serversChanged() { applyServers(Why::SettingsChanged); }
+
    // A Saved Network was added: try it now rather than after the retry delay.
    void savedNetworksChanged() { controller_.retryNow(millis()); }

@@ -47,6 +68,9 @@ class WifiService : public Service {
    void startScan(int channel = 0);
    void finishScan(uint32_t nowMs);
    void startNtp();
+    void join(const std::string& ssid, const std::string& password);
+    enum class Why { Joined, SettingsChanged, Check };
+    void applyServers(Why why);  // DNS and NTP, as Settings and the network say

    Settings& settings_;
    SavedNetworks& saved_;
@@ -58,6 +82,10 @@ class WifiService : public Service {
    uint32_t listScanSeq_ = 0;
    bool ntpWaiting_ = false;
    bool radioInitialised_ = false;
+    bool fixed_ = false;           // the network in use has a Fixed address
+    bool dnsFromSettings_ = false;
+    std::string ntpNames_[2];      // lwIP keeps the pointers, so the names live here
+    uint32_t serversCheckedMs_ = 0;
 };

 }  // namespace roro
@@ -0,0 +1,101 @@
+#include <unity.h>
+
+#include <string>
+
+#include "ipv4.h"
+
+using namespace roro::net;
+
+void setUp() {}
+void tearDown() {}
+
+static uint32_t ip(const char* s) {
+    uint32_t a = 0;
+    TEST_ASSERT_TRUE_MESSAGE(parseIpv4(s, a), s);
+    return a;
+}
+
+void test_parse_and_format() {
+    TEST_ASSERT_EQUAL_HEX32(0x0A27270C, ip("10.39.39.12"));
+    TEST_ASSERT_EQUAL_HEX32(0x00000000, ip("0.0.0.0"));
+    TEST_ASSERT_EQUAL_HEX32(0xFFFFFFFF, ip("255.255.255.255"));
+    TEST_ASSERT_EQUAL_STRING("10.39.39.12", formatIpv4(0x0A27270C).c_str());
+    TEST_ASSERT_EQUAL_STRING("192.168.1.254", formatIpv4(ip("192.168.1.254")).c_str());
+}
+
+void test_parse_refuses() {
+    uint32_t a;
+    for (const char* bad : {"", "10.39.39", "10.39.39.12.1", "10.39.39.256", "10..39.12", "10.39.39.", ".10.39.39",
+                            "10.39.39.1a", " 10.39.39.12", "10.39.39.12 ", "1.2.3.-4", "01234.1.1.1", "1.2.3.4/24"})
+        TEST_ASSERT_FALSE_MESSAGE(parseIpv4(bad, a), bad);
+}
+
+void test_prefix_and_mask() {
+    TEST_ASSERT_EQUAL_HEX32(0xFFFFFF00, maskOf(24));
+    TEST_ASSERT_EQUAL_HEX32(0xFFFFFFFC, maskOf(30));
+    TEST_ASSERT_EQUAL_HEX32(0x80000000, maskOf(1));
+    TEST_ASSERT_EQUAL_HEX32(0xFFFF0000, maskOf(16));
+    TEST_ASSERT_EQUAL_STRING("255.255.255.0", formatIpv4(maskOf(24)).c_str());
+}
+
+// Q111: what a Fixed setting must satisfy, and the reason given when it doesn't.
+void test_fixed_setting_accepted() {
+    TEST_ASSERT_EQUAL_STRING("", checkFixed({ip("10.39.39.13"), 24, ip("10.39.39.1")}).c_str());
+    TEST_ASSERT_EQUAL_STRING("", checkFixed({ip("192.168.4.2"), 30, ip("192.168.4.1")}).c_str());
+    TEST_ASSERT_EQUAL_STRING("", checkFixed({ip("10.0.0.5"), 8, 0}).c_str());  // Q107: no gateway is fine
+}
+
+void test_fixed_setting_refused() {
+    TEST_ASSERT_EQUAL_STRING("The prefix must be 1 to 30", checkFixed({ip("10.39.39.13"), 0, 0}).c_str());
+    TEST_ASSERT_EQUAL_STRING("The prefix must be 1 to 30", checkFixed({ip("10.39.39.13"), 31, 0}).c_str());
+    TEST_ASSERT_EQUAL_STRING("10.39.39.0 is the network's own address", checkFixed({ip("10.39.39.0"), 24, 0}).c_str());
+    TEST_ASSERT_EQUAL_STRING("10.39.39.255 is the broadcast address", checkFixed({ip("10.39.39.255"), 24, 0}).c_str());
+    TEST_ASSERT_EQUAL_STRING("The gateway 10.39.40.1 isn't in 10.39.39.0/24",
+                             checkFixed({ip("10.39.39.13"), 24, ip("10.39.40.1")}).c_str());
+    TEST_ASSERT_EQUAL_STRING("The gateway can't be this device's address",
+                             checkFixed({ip("10.39.39.13"), 24, ip("10.39.39.13")}).c_str());
+    TEST_ASSERT_EQUAL_STRING("The gateway 10.39.39.255 is the broadcast address",
+                             checkFixed({ip("10.39.39.13"), 24, ip("10.39.39.255")}).c_str());
+    TEST_ASSERT_EQUAL_STRING("0.0.0.0 isn't an address a device can have", checkFixed({0, 24, 0}).c_str());
+}
+
+// How a Fixed setting is typed on the console and kept in flash: "address/prefix [gateway]".
+void test_fixed_setting_as_text() {
+    FixedIp f;
+    TEST_ASSERT_EQUAL_STRING("", parseFixed("10.39.39.13/24 10.39.39.1", f).c_str());
+    TEST_ASSERT_EQUAL_HEX32(ip("10.39.39.13"), f.address);
+    TEST_ASSERT_EQUAL_UINT8(24, f.prefix);
+    TEST_ASSERT_EQUAL_HEX32(ip("10.39.39.1"), f.gateway);
+    TEST_ASSERT_EQUAL_STRING("10.39.39.13/24 10.39.39.1", formatFixed(f).c_str());
+
+    TEST_ASSERT_EQUAL_STRING("", parseFixed("192.168.4.2/30", f).c_str());
+    TEST_ASSERT_EQUAL_HEX32(0, f.gateway);
+    TEST_ASSERT_EQUAL_STRING("192.168.4.2/30", formatFixed(f).c_str());
+
+    TEST_ASSERT_EQUAL_STRING("Write it as address/prefix, then the gateway if there is one", parseFixed("10.39.39.13", f).c_str());
+    TEST_ASSERT_EQUAL_STRING("10.39.39.300 isn't an IPv4 address", parseFixed("10.39.39.300/24", f).c_str());
+    TEST_ASSERT_EQUAL_STRING("The prefix must be 1 to 30", parseFixed("10.39.39.13/abc", f).c_str());
+    TEST_ASSERT_EQUAL_STRING("gw isn't an IPv4 address", parseFixed("10.39.39.13/24 gw", f).c_str());
+    TEST_ASSERT_EQUAL_STRING("The gateway 10.39.40.1 isn't in 10.39.39.0/24", parseFixed("10.39.39.13/24 10.39.40.1", f).c_str());
+}
+
+// An NTP server is an address or a host name (Q110).
+void test_host_names() {
+    for (const char* good : {"pool.ntp.org", "time.cloudflare.com", "10.39.39.1", "ntp", "a-b.example", "0.be.pool.ntp.org"})
+        TEST_ASSERT_TRUE_MESSAGE(validHost(good), good);
+    for (const char* bad : {"", "pool .ntp.org", "-ntp.org", "ntp-.org", "ntp..org", ".ntp.org", "ntp.org.", "n_tp.org", "häst.se",
+                            "999.1.1.1", "1.2.3"})
+        TEST_ASSERT_FALSE_MESSAGE(validHost(bad), bad);
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_parse_and_format);
+    RUN_TEST(test_parse_refuses);
+    RUN_TEST(test_prefix_and_mask);
+    RUN_TEST(test_fixed_setting_accepted);
+    RUN_TEST(test_fixed_setting_refused);
+    RUN_TEST(test_fixed_setting_as_text);
+    RUN_TEST(test_host_names);
+    return UNITY_END();
+}
@@ -97,6 +97,76 @@ void test_find() {
    TEST_ASSERT_NULL(n.find("other"));
 }

+// S1, Q105: each Saved Network is Automatic (DHCP) or Fixed, and remembers which.
+void test_new_network_is_automatic() {
+    MemoryStore store;
+    SavedNetworks nets(store);
+    nets.add("home", "password1");
+    TEST_ASSERT_FALSE(nets.find("home")->fixed);
+}
+
+void test_ip_setting_survives_reload() {
+    MemoryStore store;
+    SavedNetworks nets(store);
+    nets.add("home", "password1");
+    nets.add("bench", "");
+    roro::net::FixedIp f;
+    TEST_ASSERT_EQUAL_STRING("", roro::net::parseFixed("10.39.39.13/24 10.39.39.1", f).c_str());
+    TEST_ASSERT_EQUAL_STRING("", nets.setIp("bench", &f).c_str());
+
+    SavedNetworks again(store);
+    again.load();
+    TEST_ASSERT_FALSE(again.find("home")->fixed);
+    TEST_ASSERT_TRUE(again.find("bench")->fixed);
+    TEST_ASSERT_EQUAL_STRING("10.39.39.13/24 10.39.39.1", roro::net::formatFixed(again.find("bench")->ip).c_str());
+
+    TEST_ASSERT_EQUAL_STRING("", again.setIp("bench", nullptr).c_str());  // back to Automatic
+    SavedNetworks third(store);
+    third.load();
+    TEST_ASSERT_FALSE(third.find("bench")->fixed);
+}
+
+void test_ip_setting_is_checked() {
+    MemoryStore store;
+    SavedNetworks nets(store);
+    nets.add("bench", "");
+    roro::net::FixedIp bad{0x0A272700, 24, 0};  // 10.39.39.0: the network's own address
+    TEST_ASSERT_EQUAL_STRING("10.39.39.0 is the network's own address", nets.setIp("bench", &bad).c_str());
+    TEST_ASSERT_FALSE(nets.find("bench")->fixed);
+    roro::net::FixedIp ok{0x0A27270D, 24, 0};
+    TEST_ASSERT_EQUAL_STRING("Not a saved network", nets.setIp("nowhere", &ok).c_str());
+}
+
+// Forgetting a network moves the ones after it: each keeps its own setting.
+void test_ip_setting_follows_its_network() {
+    MemoryStore store;
+    SavedNetworks nets(store);
+    nets.add("a", "");
+    nets.add("b", "");
+    nets.add("c", "");
+    roro::net::FixedIp f{0x0A27270D, 24, 0};
+    nets.setIp("c", &f);
+    nets.forget("a");
+    SavedNetworks again(store);
+    again.load();
+    TEST_ASSERT_FALSE(again.find("b")->fixed);
+    TEST_ASSERT_TRUE(again.find("c")->fixed);
+    // And changing the password keeps it.
+    again.add("c", "password2");
+    TEST_ASSERT_TRUE(again.find("c")->fixed);
+}
+
+// A stored setting that no longer passes the checks falls back to Automatic.
+void test_bad_stored_ip_setting_is_ignored() {
+    MemoryStore store;
+    SavedNetworks nets(store);
+    nets.add("bench", "");
+    store.strings["net0_ip"] = "10.39.39.13/99";
+    SavedNetworks again(store);
+    again.load();
+    TEST_ASSERT_FALSE(again.find("bench")->fixed);
+}
+
 int main() {
    UNITY_BEGIN();
    RUN_TEST(test_empty_store_has_no_networks);
@@ -107,5 +177,10 @@ int main() {
    RUN_TEST(test_validation_follows_wifi_limits);
    RUN_TEST(test_hidden_flag_survives_reload);
    RUN_TEST(test_find);
+    RUN_TEST(test_new_network_is_automatic);
+    RUN_TEST(test_ip_setting_survives_reload);
+    RUN_TEST(test_ip_setting_is_checked);
+    RUN_TEST(test_ip_setting_follows_its_network);
+    RUN_TEST(test_bad_stored_ip_setting_is_ignored);
    return UNITY_END();
 }
@@ -0,0 +1,54 @@
+#include <unity.h>
+
+#include "sd_card_id.h"
+
+using namespace roro;
+
+void setUp() {}
+void tearDown() {}
+
+// A SanDisk 8 GB card's CID: manufacturer 0x03, OEM "SD", product "SU08G", revision 8.0,
+// serial 0x1234ABCD, made in March 2014.
+static const uint8_t kSanDisk[16] = {0x03, 'S', 'D', 'S', 'U', '0', '8', 'G', 0x80,
+                                     0x12, 0x34, 0xAB, 0xCD, 0x00, 0xE3, 0xFF};
+
+void test_fields() {
+    SdCardId id = parseSdCid(kSanDisk);
+    TEST_ASSERT_EQUAL_HEX8(0x03, id.manufacturer);
+    TEST_ASSERT_EQUAL_STRING("SD", id.oem);
+    TEST_ASSERT_EQUAL_STRING("SU08G", id.product);
+    TEST_ASSERT_EQUAL_UINT8(8, id.revisionMajor);
+    TEST_ASSERT_EQUAL_UINT8(0, id.revisionMinor);
+    TEST_ASSERT_EQUAL_HEX32(0x1234ABCD, id.serial);
+    TEST_ASSERT_EQUAL_INT(2014, id.year);
+    TEST_ASSERT_EQUAL_INT(3, id.month);
+}
+
+// Clone cards put anything in the name: unprintable bytes mustn't reach the console.
+void test_unprintable_names() {
+    uint8_t cid[16] = {0x00, 0x00, 0x01, 'A', 0x00, 0xFF, 'B', ' ', 0x10};
+    SdCardId id = parseSdCid(cid);
+    TEST_ASSERT_EQUAL_STRING("??", id.oem);
+    TEST_ASSERT_EQUAL_STRING("A??B ", id.product);
+    TEST_ASSERT_EQUAL_UINT8(1, id.revisionMajor);
+}
+
+void test_manufacturer_names() {
+    TEST_ASSERT_EQUAL_STRING("SanDisk", sdManufacturerName(0x03));
+    TEST_ASSERT_EQUAL_STRING("Samsung", sdManufacturerName(0x1B));
+    TEST_ASSERT_EQUAL_STRING("unknown", sdManufacturerName(0xEE));
+}
+
+void test_summary_line() {
+    TEST_ASSERT_EQUAL_STRING("SanDisk (0x03) \"SD\" \"SU08G\" rev 8.0, serial 1234abcd, made 2014-03",
+                             sdCardSummary(parseSdCid(kSanDisk)).c_str());
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_fields);
+    RUN_TEST(test_unprintable_names);
+    RUN_TEST(test_manufacturer_names);
+    RUN_TEST(test_summary_line);
+    return UNITY_END();
+}
@@ -154,6 +154,37 @@ void test_storage_keys_fit_nvs_limit() {
        TEST_ASSERT_TRUE(std::strlen(Settings::key(static_cast<Setting>(i))) <= 15);
 }

+// S1, Q108 to Q110: DNS and NTP servers, with public defaults.
+void test_dns_and_ntp_defaults() {
+    MemoryStore store;
+    EventBus bus;
+    Settings s(store, bus);
+    s.load();
+    TEST_ASSERT_EQUAL_STRING("9.9.9.9", s.getString(Setting::Dns1).c_str());
+    TEST_ASSERT_EQUAL_STRING("1.1.1.1", s.getString(Setting::Dns2).c_str());
+    TEST_ASSERT_FALSE(s.getBool(Setting::DnsAlways));
+    TEST_ASSERT_EQUAL_STRING("pool.ntp.org", s.getString(Setting::Ntp1).c_str());
+    TEST_ASSERT_EQUAL_STRING("time.cloudflare.com", s.getString(Setting::Ntp2).c_str());
+}
+
+void test_dns_and_ntp_are_checked() {
+    MemoryStore store;
+    EventBus bus;
+    Settings s(store, bus);
+    s.load();
+    TEST_ASSERT_TRUE(s.setString(Setting::Dns1, "10.39.39.1"));
+    TEST_ASSERT_FALSE(s.setString(Setting::Dns1, "dns.example"));  // an address, not a name
+    TEST_ASSERT_FALSE(s.setString(Setting::Dns1, ""));             // the first one is required
+    TEST_ASSERT_EQUAL_STRING("10.39.39.1", s.getString(Setting::Dns1).c_str());
+    TEST_ASSERT_TRUE(s.setString(Setting::Dns2, ""));              // the second is optional
+    TEST_ASSERT_FALSE(s.setString(Setting::Dns2, "1.1.1"));
+    TEST_ASSERT_TRUE(s.setString(Setting::Ntp1, "10.39.39.1"));
+    TEST_ASSERT_TRUE(s.setString(Setting::Ntp1, "0.be.pool.ntp.org"));
+    TEST_ASSERT_FALSE(s.setString(Setting::Ntp1, "time server"));
+    TEST_ASSERT_FALSE(s.setString(Setting::Ntp1, ""));
+    TEST_ASSERT_TRUE(s.setString(Setting::Ntp2, ""));
+}
+
 int main() {
    UNITY_BEGIN();
    RUN_TEST(test_defaults_when_store_is_empty);
@@ -168,5 +199,7 @@ int main() {
    RUN_TEST(test_change_publishes_setting_changed_once);
    RUN_TEST(test_transmit_requires_confirmed_region);
    RUN_TEST(test_storage_keys_fit_nvs_limit);
+    RUN_TEST(test_dns_and_ntp_defaults);
+    RUN_TEST(test_dns_and_ntp_are_checked);
    return UNITY_END();
 }
Author	SHA1	Message	Date
twislaandClaude Opus 5.5	f834095ee3	Merge branch 's1': fixed IPv4 addresses, DNS and NTP servers Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-06 00:48:41 +02:00
twislaandClaude Opus 5.5	acf7697bdc	S1 #7 step 4: fixed IPv4, DNS and NTP in Settings Enter on a Saved Network opens its page instead of asking to forget it: "IP address" switches between Automatic and Fixed, with an address, a prefix and an optional gateway. Fixed starts from what the network is giving the device; the draft is checked and applied on leaving the page, so a half-typed address is never used. "DNS and NTP" holds the two DNS servers, "Always use my DNS" and the two NTP servers. Enter on Status shows the connection's details and where each value came from. Address fields take digits and dots only; refusals show as Toasts. Checked on the device through the screens: Fixed 10.39.39.13 applied and reverted to Automatic, a prefix of 99 refused. Measurements in docs/milestones/S1.md. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-06 00:04:53 +02:00
twislaandClaude Opus 5.5	3e279738b6	S1 #7 step 3: the Wi-Fi Service applies IP, DNS and NTP settings Joining a Saved Network uses its Fixed address, mask and gateway, or DHCP. DNS comes from Settings on Fixed networks and when "Always use my DNS" is on; NTP servers come from Settings, after any that DHCP offered. Both are re-checked every 30 s, since a DHCP renewal puts DHCP's DNS back and clears the NTP slots it didn't fill. `wifi status` shows what's in use, where it came from, and which NTP servers answered; `wifi ip`, `wifi dns`, `wifi ntp`. Debug Builds: `wifi ip ... try <s>` reverts unless kept. On knbg-guests (10.39.39.0/24, gateway .1): Fixed .12 and .13 both reach the internet through 9.9.9.9; a wrong gateway on trial cut the device off and came back by itself; back to DHCP; both NTP servers answer. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 23:52:22 +02:00
twislaandClaude Opus 5.5	bdd027cb50	S1 #7 steps 1-2: IPv4 checks, the IP setting per Saved Network, DNS and NTP settings The plan and decisions Q105 to Q116 (docs/milestones/S1.md). lib/net: strict IPv4 parsing, prefix and mask, and the checks a Fixed setting must pass, each refusal with its reason. A Saved Network is Automatic or Fixed (address/prefix and an optional gateway), kept with it in flash. Settings: two DNS servers (9.9.9.9, 1.1.1.1), "Always use my DNS", two NTP servers (pool.ntp.org, time.cloudflare.com). Host-tested: 383 tests. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 23:39:07 +02:00
twislaandClaude Opus 5.5	7e8882d9cb	Merge branch 's1': the SD driver's ready test, and `sd card` Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 23:25:55 +02:00
twislaandClaude Opus 5.5	7b2cf88a0a	ADR 0007: link the upstream report and the issue that follows it Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 23:16:17 +02:00
twislaandClaude Opus 5.5	370f067fbf	`sd card`: what the card says it is, from its CID register Type, size, and the identity register read by our SD driver (CMD10): manufacturer, OEM, product name, revision, serial and date, decoded by a host-tested parser. Needed for the upstream report of #21: nothing else here could read the card's identity. This one is a Samsung 8 GB SDHC from June 2013. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 23:15:29 +02:00
twislaandClaude Opus 5.5	3f2650c56e	SD driver: a dummy byte before the ready test; say why a write failed (#21 ) The card "refused" a write about once in 2,000 multi-block writes: three 1.7 MB uploads in ten. Measured with a driver that records where it gives up: every time, all blocks were accepted, and the status check after Stop Tran came back as 0xFF or 0x1F. The driver tests for ready with the first byte after selecting the card, which reads 0xFF before the card has signalled busy, so CMD13 went out mid-programming. A dummy byte first, as in ChaN's reference driver, and one after Stop Tran. 30 uploads in a row since, each read back by SHA-256, ten with the radio listening: no fault. 10 MHz made no difference; the card stays at 20 MHz. `info` shows the driver's write faults; `put` prints the step and the card's answer when one happens. ADR 0007. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 22:55:02 +02:00
twislaandClaude Opus 5.5	3ee7ae1097	lib/SD: Arduino-ESP32 3.3.12's SD library, as it comes A project library named SD takes the framework's place at link time. Unchanged here (Apache-2.0), so that the next commit shows exactly what roro9stack changes in it, and a later framework update can be compared. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT	2026-10-05 22:51:59 +02:00