feat(safety): remote e-stop over 4G MQTT (Issue #63)
STM32 firmware:
- safety.h/c: EstopSource enum, safety_remote_estop/clear/get/active()
CDC 'E'=ESTOP_REMOTE, 'F'=ESTOP_CELLULAR_TIMEOUT, 'Z'=clear latch
- usbd_cdc_if: cdc_estop_request/cdc_estop_clear_request volatile flags
- status: status_update() +remote_estop param; both LEDs fast-blink 200ms
- main.c: immediate motor cutoff highest-priority; arming gated by
!safety_remote_estop_active(); motor estop auto-clear gated; telemetry
'es' field 0-4; status_update() updated to 5 args
Safety: IMMEDIATE motor cutoff, latched until explicit Z + DISARMED,
cannot re-arm via MQTT alone (requires RC arm hold). IWDG-safe.
Jetson bridge:
- remote_estop_node.py: paho-mqtt + pyserial, cellular watchdog 5s
- estop_params.yaml, remote_estop.launch.py
- setup.py / package.xml: register node + paho-mqtt dep
- docker-compose.yml: remote-estop service
- test_remote_estop.py: kill/clear/watchdog/latency unit tests
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-firmware
3a7576939e