feat(bridge): binary STM32 command protocol (Issue #119)
Add stm32_protocol.py — pure-Python binary frame codec:
- Frame: STX(0x02)+TYPE+LEN+PAYLOAD+CRC16-CCITT(BE)+ETX(0x03)
- CRC covers TYPE+LEN+PAYLOAD; polynomial 0x1021, init 0xFFFF
- Encoders: HEARTBEAT, SPEED_STEER(-1000..+1000 int16), ARM, SET_MODE, PID_UPDATE
- Telemetry decoders: ImuFrame, BatteryFrame, MotorRpmFrame, ArmStateFrame, ErrorFrame
- FrameParser: streaming byte-by-byte state machine, resync on corrupt data
Add stm32_cmd_node.py — ROS2 bidirectional bridge node:
- /cmd_vel → SPEED_STEER at up to 50 Hz
- HEARTBEAT timer (default 200ms); STM32 watchdog fires at 500ms
- Jetson-side watchdog: no /cmd_vel for 500ms → send SPEED_STEER(0,0)
- /saltybot/arm service (SetBool) → ARM frame
- /saltybot/pid_update topic → PID_UPDATE frame
- Telemetry RX: IMU→/saltybot/imu, BATTERY→/saltybot/telemetry/battery,
MOTOR_RPM→/saltybot/telemetry/motor_rpm, ARM_STATE→/saltybot/arm_state,
ERROR→/saltybot/error
- Auto-reconnect on USB disconnect (serial.SerialException caught)
- Zero-speed + disarm sent on node shutdown
- /diagnostics with serial health, frame counts, last cmd age
Add test_stm32_protocol.py (60+ tests):
- CRC16-CCITT correctness, known test vectors
- All encoder output structures and payload values
- FrameParser: all telemetry types, bad CRC, bad ETX, resync, streaming,
oversized payload, frame counters, reset
Add test_stm32_cmd_node.py (30+ tests):
- MockSerial: TX/RX byte-level testing without hardware
- Speed/steer clamping, scaling, frame structure
- Watchdog fires/doesn't fire relative to timeout
- CRC error counted, resync after garbage
Add stm32_cmd_params.yaml, stm32_cmd.launch.py.
Update package.xml (add std_srvs, geometry_msgs deps).
Update setup.py (add stm32_cmd_node entry point + new config/launch).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-jetson
30be0d8cd3