Sensor Board Protobuf
This page: Complete protobuf message definitions for the sensor_board component.
The protobuffers for the sensor_board are passed between embedded, the network, and other boards for diagnostics and data collection. This page documents the actual message definitions from the ERC-Protobufs repository.
Common Definitions (sensor.proto)
Location: ERC-Protobufs/components/sensor_board/sensor.proto
SensorState Enum
enum SensorState {
SENSOR_IDLE = 0; // Sensor is idle/not currently sampling
SENSOR_OPERATING = 1; // Sensor is actively sampling/operating normally
SENSOR_CALIBRATING = 2; // Sensor is in calibration mode
SENSOR_ERROR = 3; // Sensor has encountered an error
}GPS Sensor (gps_sensor.proto)
Location: ERC-Protobufs/components/sensor_board/gps_sensor.proto
Direction: Sensor Board → Navigation/Localization Systems
GPSFixQuality Enum
Indicates the type and quality of GPS fix obtained.
enum GPSFixQuality {
NO_FIX = 0; // No fix available
GPS_FIX = 1; // Standard GPS fix
DGPS_FIX = 2; // Differential GPS fix
PPS_FIX = 3; // PPS (Pulse Per Second) fix
RTK_FIX = 4; // Real-Time Kinematic fix
RTK_FLOAT = 5; // RTK float solution
}GPSErrorCode Enum
Detailed error codes for GPS/GNSS sensor failures.
enum GPSErrorCode {
GPS_NO_ERROR = 0;
GPS_COMMUNICATION_FAILURE = 1; // UART connection lost
GPS_INVALID_DATA = 2; // Data parsing or validation failed
GPS_ANTENNA_FAULT = 3; // GPS antenna disconnected or faulty
GPS_LOW_SIGNAL_QUALITY = 4; // Signal strength too weak for fix
}SensorBoardGPSInfo Message
Complete GPS positioning and velocity information.
message SensorBoardGPSInfo {
// GPS coordinates
double latitude = 1; // Degrees (positive = North, negative = South)
double longitude = 2; // Degrees (positive = East, negative = West)
float altitude = 3; // Meters above sea level
// Velocity data
float speed = 4; // Speed in meters per second
float heading = 5; // Course over ground in degrees (0-360)
// Position accuracy and quality
float hdop = 6; // Horizontal dilution of precision (lower is better)
float vdop = 7; // Vertical dilution of precision (lower is better)
int32 satellites = 8; // Number of satellites in view (up to 16)
GPSFixQuality fix_quality = 9;
SensorState state = 10;
GPSErrorCode error_code = 11; // Error code if state is SENSOR_ERROR
// Timestamp from GPS
int64 utc_timestamp = 12; // Unix timestamp in milliseconds
}IMU Sensor (imu_sensor.proto)
Location: ERC-Protobufs/components/sensor_board/imu_sensor.proto
Direction: Sensor Board → Motion Control/Attitude Systems
IMUErrorCode Enum
Detailed error codes for IMU sensor failures.
enum IMUErrorCode {
IMU_NO_ERROR = 0;
IMU_COMMUNICATION_FAILURE = 1; // I2C/SPI connection lost
IMU_CALIBRATION_REQUIRED = 2; // Sensor needs calibration
IMU_CALIBRATION_FAILED = 3; // Calibration procedure failed
IMU_INVALID_DATA = 4; // Data out of valid range
IMU_SENSOR_FAULT = 5; // Hardware fault detected
IMU_GYROSCOPE_ERROR = 6; // Gyroscope component failure
IMU_MAGNETOMETER_ERROR = 7; // Magnetometer component failure
IMU_ACCELEROMETER_ERROR = 8; // Accelerometer component failure
}SensorBoardIMUInfo Message
3-axis inertial measurement data (acceleration, angular velocity, magnetic field).
message SensorBoardIMUInfo {
// 3-Axis Accelerometer data
float accel_x = 1; // X-axis acceleration
float accel_y = 2; // Y-axis acceleration
float accel_z = 3; // Z-axis acceleration
// 3-Axis Gyroscope data
float gyro_x = 4; // X-axis angular velocity
float gyro_y = 5; // Y-axis angular velocity
float gyro_z = 6; // Z-axis angular velocity
// 3-Axis Magnetometer data (9-axis IMU only)
float mag_x = 7; // X-axis magnetic field
float mag_y = 8; // Y-axis magnetic field
float mag_z = 9; // Z-axis magnetic field
bool is_calibrated = 13; // True if IMU has been calibrated on level surface
SensorState state = 14;
IMUErrorCode error_code = 15; // Error code if state is SENSOR_ERROR
}pH Sensor (ph_sensor.proto)
Location: ERC-Protobufs/components/sensor_board/ph_sensor.proto
Direction: Sensor Board → Environmental Monitoring Systems
PHErrorCode Enum
Detailed error codes for pH sensor failures.
enum PHErrorCode {
PH_NO_ERROR = 0;
PH_COMMUNICATION_FAILURE = 1; // ADC connection lost
PH_OUT_OF_RANGE = 2; // Reading outside 0-14 range
PH_CALIBRATION_REQUIRED = 3; // Sensor needs calibration
PH_INVALID_DATA = 4; // Data validation failed
PH_PROBE_FAULT = 5; // Electrode fault detected
PH_TEMPERATURE_SENSOR_ERROR = 6; // Temperature compensation sensor failed
}SensorBoardPHInfo Message
Water quality measurement with temperature compensation.
message SensorBoardPHInfo {
float ph_value = 1; // Raw pH measurement (0-14 scale, 7 is neutral)
float voltage = 2; // Voltage reading from pH sensor in millivolts
float temperature = 3; // Temperature reading in Celsius (if external sensor available)
SensorState state = 4; // Current state of the pH sensor
PHErrorCode error_code = 5; // Error code if state is SENSOR_ERROR
}Notes:
- pH value is derived from voltage via linear calibration equation
- 40-sample moving average applied internally to reduce ADC noise
- Temperature used for automatic compensation (default ~25°C)
Load Cell Sensor (load_cell.proto)
Location: ERC-Protobufs/components/sensor_board/load_cell.proto
Direction: Sensor Board → Arm Control/Gripper Systems
LoadCellErrorCode Enum
Detailed error codes for load cell sensor failures.
enum LoadCellErrorCode {
LOAD_CELL_NO_ERROR = 0;
LOAD_CELL_COMMUNICATION_FAILURE = 1; // ADC connection lost
LOAD_CELL_OUT_OF_RANGE = 2; // Force measurement exceeds limits
LOAD_CELL_CALIBRATION_REQUIRED = 3; // Sensor needs calibration
LOAD_CELL_INVALID_DATA = 4; // Data validation failed
LOAD_CELL_SENSOR_FAULT = 5; // Hardware fault detected
}SensorBoardLoadCellInfo Message
Force measurement for robotic gripper control and load monitoring.
message SensorBoardLoadCellInfo {
uint32 sensor_index = 1; // 0-based index of the load cell (0 or 1)
float force_newtons = 2; // Force in Newtons
float mass_grams = 3; // Mass in grams (derived from force)
int32 raw_counts = 4; // Raw ADC counts (for debugging)
// Calibration status and parameters
bool is_calibrated = 5; // True if calibration parameters are valid
float scale_newtons_per_count = 6; // Conversion factor (N/count)
int32 tare_offset_counts = 7; // Zero-load ADC offset
SensorState state = 8;
LoadCellErrorCode error_code = 9; // Error code if state is SENSOR_ERROR
}Dual Sensor Support:
- Up to 2 independent load cells (sensor_index 0 and 1)
- Typically used on dual-pad grippers for load distribution feedback
- Each sensor maintains independent calibration parameters
- Enables slip detection via load imbalance analysis
Pressure Sensor (pressure_sensor.proto)
Location: ERC-Protobufs/components/sensor_board/pressure_sensor.proto
Direction: Sensor Board → Arm Control/Gripper Systems / Environmental Monitoring
PressureErrorCode Enum
Detailed error codes for pressure sensor failures.
enum PressureErrorCode {
PRESSURE_NO_ERROR = 0;
PRESSURE_COMMUNICATION_FAILURE = 1; // I2C/ADC connection lost
PRESSURE_OUT_OF_RANGE = 2; // Reading exceeds sensor limits
PRESSURE_CALIBRATION_REQUIRED = 3; // Sensor needs calibration
PRESSURE_INVALID_DATA = 4; // Data validation failed
PRESSURE_SENSOR_FAULT = 5; // Hardware fault detected
}SensorBoardPressureInfo Message
Pressure measurement for robotic gripper control and environmental sensing.
message SensorBoardPressureInfo {
uint32 sensor_index = 1; // 0-based index of the pressure sensor (0 or 1)
// Pressure data
float pressure_kpa = 2; // Pressure in kilopascals
float temperature_c = 3; // Temperature in Celsius (if available)
float voltage = 4; // Sensor output voltage (if available)
// Calibration status
bool is_calibrated = 5; // True if calibration parameters are valid
SensorState state = 6;
PressureErrorCode error_code = 7; // Error code if state is SENSOR_ERROR
}Dual Sensor Support:
- Up to 2 independent pressure sensors (sensor_index 0 and 1)
- Primary use: gripper pad force feedback for PID control
- Enables real-time grip force regulation and slip detection
- Secondary uses: depth sensing, altitude sensing, system pressure monitoring
Board Diagnostics (diagnostics.proto)
Location: ERC-Protobufs/components/sensor_board/diagnostics.proto
Direction: Sensor Board → Debugging Board / Health Monitoring Systems
SensorBoardDiagnostics Message
Complete system health and status snapshot sent periodically (5 second default).
message SensorBoardDiagnostics {
enum State {
IDLE = 0;
OPERATING = 1;
CALIBRATING = 2;
ERROR = 3;
}
State state = 1; // Overall board state
SensorBoardPHInfo ph_sensor = 2; // pH sensor status
SensorBoardIMUInfo imu_sensor = 3; // IMU sensor status
// Overall sensor board health
float board_temperature = 4; // Board temperature in Celsius
float board_voltage = 5; // System voltage (3.3V supply)
SensorBoardGPSInfo gps_sensor_1 = 6; // GPS sensor status
}Board States:
- IDLE (0) - Board initialized but not actively polling sensors
- OPERATING (1) - All sensors functioning normally, data being collected
- CALIBRATING (2) - Board or sensors in calibration mode
- ERROR (3) - Critical system failure detected
Health Indicators:
- board_temperature - STM32H753 die temperature; normal range 25-75°C
- board_voltage - 3.3V supply input; should be 3.0-3.6V
- Embedded sensor states - Each sensor's current SensorState (IDLE/OPERATING/CALIBRATING/ERROR)
Error Code Pattern
All sensor error codes follow a consistent pattern:
enum XXXErrorCode {
XXX_NO_ERROR = 0; // No error
XXX_COMMUNICATION_FAILURE = 1; // Hardware interface (I2C/SPI/UART/ADC) failure
XXX_OUT_OF_RANGE = 2; // Reading outside valid sensor range
XXX_CALIBRATION_REQUIRED = 3; // Sensor needs calibration
XXX_INVALID_DATA = 4; // Data validation/filtering failed
XXX_SENSOR_FAULT = 5; // Hardware fault or component failure
// Additional sensor-specific errors...
}Integration into application:
if (gps_result.error_code == GPS_COMMUNICATION_FAILURE) {
LOG_ERROR("GPS UART connection lost");
diagnostics.gps_sensor_1.state = SENSOR_ERROR;
} else if (gps_result.error_code == GPS_NO_ERROR) {
LOG_INFO("GPS position: %f, %f", gps_result.latitude, gps_result.longitude);
}Network Transmission
Main Sensor Data:
- Sent via individual sensor messages
- Packaged into SensorBoardState (sensor.proto)
- UDP broadcast to 192.168.0.255:7 (configurable)
- Interval: 5 seconds default (configurable)
- Encoding: Nanopb (lightweight protobuf for embedded)
Diagnostics Data:
- Sent via SensorBoardDiagnostics message
- UDP broadcast to 192.168.0.255:7 (same port)
- Interval: 5 seconds (synced with main loop)
- Contains snapshot of all sensor states + health metrics
Message Composition
The SensorBoardDiagnostics message is composed of individual sensor message types:
SensorBoardDiagnostics
├── state (Board state)
├── SensorBoardPHInfo
│ ├── ph_value
│ ├── voltage
│ ├── temperature
│ ├── state (SensorState)
│ └── error_code (PHErrorCode)
├── SensorBoardIMUInfo
│ ├── accel_x, accel_y, accel_z
│ ├── gyro_x, gyro_y, gyro_z
│ ├── mag_x, mag_y, mag_z
│ ├── is_calibrated
│ ├── state (SensorState)
│ └── error_code (IMUErrorCode)
├── board_temperature
├── board_voltage
└── SensorBoardGPSInfo
├── latitude, longitude, altitude
├── speed, heading
├── hdop, vdop, satellites
├── fix_quality
├── state (SensorState)
├── error_code (GPSErrorCode)
└── utc_timestampNote: Not all proto files define load cells and pressure sensors in diagnostics.proto yet - they are sent as separate messages when available.