Add optional FrSky SmartPort (S.Port) telemetry

[robthomson]

Add optional FrSky SmartPort (S.Port) telemetry

Branch: sport → main

Summary

Adds FrSky S.Port ESC slave telemetry as an optional compile-time feature. When enabled, the ESC responds to S.Port polls from a FrSky/ELRS receiver directly, replacing KISS telemetry on the signal wire. All existing behaviour is unchanged when the flag is not set.

Build with:

make <TARGET> USE_SPORT_TELEMETRY=1

What's included

New files

• Inc/sport_telemetry.h — protocol constants and public API
• Inc/telemetry_protocol.h — baud-rate abstraction (57600 vs 115200) used by MCU UART init
• Src/sport_telemetry.c — S.Port slave state machine, frame builder, and ESC config protocol

Makefile

• USE_SPORT_TELEMETRY=1 adds -DUSE_SPORT_TELEMETRY to CFLAGS; no effect on any existing build

All MCU serial_telemetry.c files

All changes guarded by #ifdef USE_SPORT_TELEMETRY:

• GPIO reconfigured to push-pull + pull-down
• Hardware TX/RX pin inversion (STM32 G0/G4/L4/F4/F0; non-inverting targets emit a #warning — external inverter required)
• Baud rate switched to 57600
• USART direction set to RX-only at init; half-duplex switching handled in ISR/DMA callbacks
• Receive timeout (26 char periods) used to trigger response after poll is received

Mcu/g071/Src/stm32g0xx_it.c

USART1_IRQHandler added (sport only): handles RXNE byte receipt, RTO-triggered DMA transmit, and TC-triggered switchback to RX. DMA CH3 TC/TE handlers extended for sport TX teardown.

Src/main.c

Sport path clears send_telemetry flag without calling KISS functions; KISS info-packet path guarded.

Src/kiss_telemetry.c

aTxBuffer definition and KISS functions wrapped in #ifndef USE_SPORT_TELEMETRY to prevent linker conflict.

Telemetry data sent

Round-robin across 6 slots per poll:

App ID	Data
0x0B70	Temperature (°C)
0x0400	Unused
0x0210	Voltage (VFAS)
0x0200	Current
0x0B30	Fuel / mAh consumed
0x0500	eRPM

ESC config protocol

S.Port config sensor (physical ID 0x0D) supports PING / GET / SET / SAVE commands over the same wire. 28 parameters are accessible:

#	Parameter	Range	Notes
1	Motor poles	2–64
2	Reverse direction	bool	Runtime effect
3	Bidirectional	bool	Runtime effect
4	Beep volume	0–11
5	PWM frequency	8–144 kHz
6	Max ramp	1–200
7	Minimum duty	0–50
8	Sine start	bool
9	Complementary PWM	bool
10	Stuck rotor protection	bool
11	Startup power	50–150
12	Drag brake	1–10
13	Driving brake	1–10
14	Variable PWM	0–2	0=off, 1=fixed, 2=auto
15	Timing advance	0–30	User range; firmware applies +10 EEPROM offset
16	Motor kV	0–255	Raw byte; actual kV = (value × 40) + 20
17	Brake on stop	bool
18	Stall protection	bool
19	Low voltage cutoff	bool
20	Cell voltage floor	0–100	Raw; mV/cell = (value + 250) × 10
21	RC car reverse	bool
22	Hall sensors	bool
23	Sine changeover	5–25%
24	Temperature limit	70–255°C	255 = disabled
25	Current limit	0–100 A	0 = disabled
26	Sine power	1–10
27	Input type	0–5	0=Auto, 1=DShot, 2=Servo, 3=Serial, 4=EDT Arm, 5=DroneCAN
28	Auto advance	bool

advance_level is exposed as user range 0–30; the firmware transparently applies the +10 EEPROM offset, consistent with the DroneCAN parameter table.

Configuration

An ethos lua app to configure the esc via s.port can be found here

https://github.com/robthomson/am32-ethos-configurator

Tested on

• SEQURE_HV_G071 (STM32G071, 64KB flash) with FrSky receiver

[robthomson]

In an idea world for this PR; the epprom would have change to allow the protocol to be set.