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README.md

BME68X Sample ─ TPHG measurements with the BME68X Sensor API

Sample application for periodic temperature, pressure, humidity and gas resistance measurements, in forced mode with a single heater set-point.

This is basically a port of the forced mode example program that comes with the BME68X Sensor API.

Tip

Use this application to test communication interface configurations.

Configuration

Communication interface

This sample application relies on drivers/bme68x-sensor-api to communicate with the BME680/688 device.

The communication interface must be described in the devicetree, typically with an overlay file, e.g.:

/* I2C bus the BME680/688 device is connected to. */
&i2c0 {
    bme680@76 {
        compatible = "bosch,bme68x-sensor-api";

        /* BME68X I2C slave address (0x76 or 0x77) */
        reg = < 0x76 >;
    };
};

See also Use devicetree overlays if this does not sound familiar.

Sensor

The sensor is configured with Kconfig options.

Kconfig Configuration
BME68X_TPHG_SAMPLE_RATE Measurements period (seconds)
BME68X_TPHG_AMBIENT_TEMP (=25) Initial ambient temperature estimate
BME68X_TPHG_TEMP_OS_{NONE,1X,...,16X} (=2X) Temperature oversampling
BME68X_TPHG_PRESS_OS_{NONE,1X,...,16X} (=16X) Pressure oversampling
BME68X_TPHG_HUM_OS_{NONE,1X,...,16X} (=1X) Humidity oversampling
BME68X_TPHG_FILTER_{OFF,...,128} (=OFF) IIR filter
BME68X_TPHG_HEATR_TEMP (=320) Heater set-point in degree Celsius
BME68X_TPHG_HEATR_DUR (=197) Heating duration in millisecond
BME68X_TPHG_LOG_LEVEL Application log level

For example, in prj.conf:

# Enable IIR filter
CONFIG_BME68X_TPHG_FILTER_2=y

# ULP mode.
CONFIG_BME68X_TPHG_ULP=y

Configuration options are also accessible via the Kconfig menu: BME68X Sample - TPHG

Tip

The default configuration should be just fine for testing purpose.

Building and running

Nothing unusual, e:g:

$ cd bme68x-zephyr
$ west build samples/bme68x-tphg -t menuconfig
$ west flash

Console output:

*** Booting Zephyr OS build v3.6.0 ***
[00:00:00.257,263] <inf> bme68x_sensor_api: bme680@77 (Fixed-point API)
[00:00:00.294,769] <inf> bme68x_tphg: os_t:x2 os_p:x16 os_h:x1 iir:off
[00:00:00.298,034] <inf> bme68x_tphg: heatr_temp:320 degC  heatr_dur:197 ms
[00:00:00.298,065] <inf> bme68x_tphg: TPHG cycle: 239590 us
[00:00:00.542,602] <inf> bme68x_tphg: T:25.86 deg C, P:101.011 kPa, H:51.381 %, G:38.524 kOhm
[00:00:03.787,231] <inf> bme68x_tphg: T:25.90 deg C, P:101.011 kPa, H:51.481 %, G:35.511 kOhm
[00:00:07.031,890] <inf> bme68x_tphg: T:25.94 deg C, P:101.013 kPa, H:51.468 %, G:35.271 kOhm
[00:00:10.276,550] <inf> bme68x_tphg: T:25.95 deg C, P:101.013 kPa, H:51.394 %, G:35.360 kOhm
[00:00:13.521,209] <inf> bme68x_tphg: T:25.96 deg C, P:101.009 kPa, H:51.328 %, G:35.271 kOhm

Tip

If the bme68x module is not installed as an external project managed by West, its path must be appended to ZEPHYR_EXTRA_MODULES:

  • in CMakeLists.txt
  • or as CMake variable, e.g. west build -- -DZEPHYR_EXTRA_MODULES=/path/to/bme68x-zephyr