Radio Service: a transmit path, behind the Region #31

New Issue

2026-10-05T20:07:18Z

twisla commented

2026-10-05 20:07:18 +00:00

What

Give the Radio Service the one thing M3 left out on purpose (Q94): sending a packet. On the radio task, with everything that must hold before a transmission checked in one place.

What's known

The radio task already owns the SX1262; transmitting is another request to it, and receiving resumes afterwards. DIO1 reports "transmit done" as it reports "receive done".
The Cap's antenna switch: DIO2 selects transmit or receive once the expander's P0 is high (M3 step 1). DIO2's part was never exercised, since nothing transmitted.
Guards: the Region confirmed (Settings::canTransmit()), the frequency inside the Region's band, the Duty Cycle Budget (#32), and the radio present. A refused transmission says why.
Transmitting into no antenna can damage the power amplifier: the RP-SMA antenna must be on.
Power: the SX1262 reaches +22 dBm; the Cap's page gives 163 mA at 5 V for the radio.
A Sweep or a Sniffer on other settings must not transmit by accident: only the Mesh Service's settings may.

Questions

Those of the design round (#30): power, listen before talk, what else guards it.

## What Give the Radio Service the one thing M3 left out on purpose (Q94): sending a packet. On the radio task, with everything that must hold before a transmission checked in one place. ## What's known - The radio task already owns the SX1262; transmitting is another request to it, and receiving resumes afterwards. DIO1 reports "transmit done" as it reports "receive done". - The Cap's antenna switch: DIO2 selects transmit or receive once the expander's P0 is high (M3 step 1). DIO2's part was never exercised, since nothing transmitted. - **Guards:** the Region confirmed (`Settings::canTransmit()`), the frequency inside the Region's band, the Duty Cycle Budget (#32), and the radio present. A refused transmission says why. - Transmitting into no antenna can damage the power amplifier: the RP-SMA antenna must be on. - Power: the SX1262 reaches +22 dBm; the Cap's page gives 163 mA at 5 V for the radio. - A Sweep or a Sniffer on other settings must not transmit by accident: only the Mesh Service's settings may. ## Questions Those of the design round (#30): power, listen before talk, what else guards it. ## Related `src/services/radio_service.h` ("no way to transmit"), `docs/milestones/M3.md` (Q94, step 1), CONTEXT.md (Region), #25, #30.

twisla added this to the M5 Mesh transmit milestone 2026-10-05 20:07:18 +00:00

twisla added the

concern/security labels 2026-10-05 20:07:18 +00:00

twisla added a new dependency 2026-10-05 20:07:19 +00:00

#25 Mesh Service: take part in the mesh, receive only