Public Access
twislaandClaude Opus 5.5
3242475699
The 16-byte clear header (hops away, channel hash, relay node), the EU_868 presets and their frequency slots, and the channel hash, all checked against Meshtastic's source. Captures are pcap with LoRaTap v0, read back with TShark 4.2.5; packet RSSI is plain dBm, as Wireshark reads it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT
39 lines
1.3 KiB
C++
39 lines
1.3 KiB
C++
#pragma once
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#include <cstddef>
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#include <cstdint>
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namespace roro::meshtastic {
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// Radio settings shared by every Meshtastic preset (firmware src/mesh/RadioInterface.h).
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constexpr uint8_t kSyncWord = 0x2B;
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constexpr uint16_t kPreambleLength = 16;
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// The default Channel key ("AQ==", expanded): public, so the default Channel is readable by anyone.
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extern const uint8_t kDefaultKey[16];
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// A modem preset: bandwidth, spreading factor and coding rate (4/cr). Named as Meshtastic shows them.
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struct Preset {
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const char* name;
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float bwKHz;
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uint8_t sf;
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uint8_t cr;
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};
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// The presets Meshtastic allows in EU_868, its order, LongFast (the default) first.
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extern const Preset kEu868Presets[];
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extern const size_t kEu868PresetCount;
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const Preset* findPreset(const char* name); // nullptr when EU_868 doesn't allow it
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// djb2, as Meshtastic hashes a Channel's name to pick a frequency slot.
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uint32_t djb2(const char* s);
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// The byte in every packet header naming its Channel: the name's bytes XORed with the key's.
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uint8_t channelHash(const char* name, const uint8_t* key, size_t keyLen);
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// EU_868 is 869.4 to 869.65 MHz: the slot comes from the Channel's name (the preset's name for
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// an unnamed Channel, which is the default).
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uint32_t eu868FrequencyHz(const Preset& preset, const char* channelName = nullptr);
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} // namespace roro::meshtastic
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