PX4 BME688 Gas Sensor Interface (NXP RDDRONE-FMUK66 Flight Controller)

NXP HoverGames #3 Details

Modular Driver integrating Bosch bme68x-sensor-api

Build sensor driver on PX4 Autopilot

1. Declare unique sensor/driver ID under drv_sensor.h - #define DRV_GAS_DEVTYPE_BME688 0xC2
2. Add submodule under PX4 directory src/drivers/gas
   • git submodule add <URL> src/drivers/gas
3. Enable BME688 driver: make <board_type> boardconfig
   • Example: make nxp_fmuk66-v3_default boardconfig
4. Sync, compile, and build PX4 for flashing

cd build && cmake ..
cd ..
make -j4 <board_type>
make <board_type> upload

Publish uORB sensor data on topic

1. Define uORB sensor topic by creating a msg file under msg/sensor_gas.msg

uint64 timestamp          # time since system start (microseconds)
uint64 timestamp_sample

uint32 device_id          # unique device ID for the sensor that does not change between power cycles

uint32 sample_count       # bme688 sample counts
float32 temperature       # temperature in degrees Celsius
float32 pressure          # static pressure measurement in Pascals
float32 humidity          # Humidity in percentage (%)
float32 gas_resistance    # gas resistance (ohm)
uint8 device_status       # byte hex 0xB0

uint32 error_count

uint8 ORB_QUEUE_LENGTH = 4

SPI interface (qGroundControl MavLink Console)

NuttShell (NSH) NuttX-11.0.0
nsh> bme688
Usage: bme688 <command> [arguments...]
 Commands:

   start
     [-I]        Internal I2C bus(es)
     [-X]        External I2C bus(es)
     [-s]        Internal SPI bus(es)
     [-S]        External SPI bus
     [-b <val>]  board-specific bus (default=all) (external SPI: n-th bus (default=1))
     [-c <val>]  chip-select pin (for internal SPI) or index (for external SPI)
     [-m <val>]  SPI mode
     [-f <val>]  bus frequency in kHz
     [-q]        quiet startup (no message if no device found)
     [-a <val>]  I2C address
                 default: 119

   stop

   status        print status info

nsh> bme688 start -S
INFO  [SPI_I2C] adding a running instance -set started to true
bme688 #0 on SPI bus 3 (external, equal to '-b 1')

nsh> bme688 status
INFO  [SPI_I2C] Running on SPI Bus 3
bme688: sample: 2 events, 3296us elapsed, 1648.00us avg, min 1150us max 2146us 704.278us rms
bme688: measure: 2 events, 287781us elapsed, 143890.50us avg, min 143870us max 143911us 36.791us rms
bme688: comms errors: 0 events

nsh> listener sensor_gas

TOPIC: sensor_gas
 sensor_gas
    timestamp: 94108924 (0.835246 seconds ago)
    timestamp_sample: 94107860 (1064 us before timestamp)
    device_id: 12714010 (Type: 0xC2, SPI:3 (0x00))
    sample_count: 1
    temperature: 23.8355
    pressure: 101309.7344
    humidity: 55.2943
    gas_resistance: 27222.4590
    error_count: 0
    device_status: 176

I2C interface (qGroundControl MavLink Console)

nsh> bme688 start -X -f 200000
NFO  [SPI_I2C] adding a running instance -set started to true
bme688 #0 on I2C bus 1 address 0x77
nsh> bme688 status
INFO  [SPI_I2C] Running on I2C Bus 1, Address 0x77
bme688: sample: 13 events, 14433us elapsed, 1110.23us avg, min 920us max 1290us 106.065us rms
bme688: measure: 14 events, 2069552us elapsed, 147825.14us avg, min 147513us max 148240us 179.129us rms
bme688: comms errors: 0 events

nsh> listener sensor_gas

TOPIC: sensor_gas
 sensor_gas
    timestamp: 185075367 (0.630325 seconds ago)
    timestamp_sample: 185074305 (1062 us before timestamp)
    device_id: 12744457 (Type: 0xC2, I2C:1 (0x77))
    sample_count: 1
    temperature: 23.7633
    pressure: 101306.1875
    humidity: 59.5401
    gas_resistance: 35814.2148
    error_count: 0
    device_status: 176