1.5 KiB
XIAO ESP32-C6 Sensor Node Protocol
The XIAO sensor node reads the BNO086 and MAX-M10S and publishes vehicle telemetry over half-duplex RS485 at 115200 8-N-1, one JSON object per line. It owns no control state. Cargo remains the controller, HTTP server, and /api/v1 source of truth; JBD/NimBLE behavior is unchanged.
The expansion-board pins are D2 driver enable, D4 TX, and D5 RX. Only physical bus ends should be terminated. Confirm A/B polarity because vendor labels vary.
Schema version 1
sensor_status includes node_id, firmware_version, uptime_ms, and:
imu:online,valid,accuracy, quaternion, yaw, pitch, and roll in degrees.gps:online,fix, satellites, NMEA character/checksum counters, latitude, longitude, altitude meters, speed kph, course degrees, and structured UTC.
online only means UART bytes arrived recently. In gps.nmea, a rising sentences_passed count proves valid NMEA at the configured baud rate. A rising character count with no passed sentences indicates wrong-baud noise or malformed data. A consistently rising failed count indicates corrupt UART data or a baud mismatch.
Consumers must check valid or fix before displaying measurements and ignore unknown fields. The native breakout coordinate frame is reported initially; installation-specific axis remapping should follow physical calibration.
This link does not replace dashboard-to-Cargo WiFi/HTTP. A future dashboard receiver may display this telemetry without moving relay, BMS, alarm, or configuration authority away from Cargo.