BME860 does not return humidity or gas-resistance

[Crackl1ng]

Hello Bosch-Community,

I'm using the BME860 with an STM32 board via I2C. Reading temperature and pressure seems to work fine, as its values seem to make sense.

But neither humidity nor gas_resistance or humidity change. Humidity also is the wrong number, since 100 % relative humidity is a little bit over the tops.

I'm using the code, which is pretty similair to the one in the application note.

float volatile temperature = 0;
float volatile pressure = 0;
float volatile humidity = 0;
float gas_resistance = 0;

struct  bme680_dev  gas_sensor;

gas_sensor.dev_id = BME680_I2C_ADDR_PRIMARY;

gas_sensor.intf = BME680_I2C_INTF;
	gas_sensor.read = bus_read;
	gas_sensor.write = bus_write;
	gas_sensor.delay_ms = HAL_Delay;
	///* amb_temp can be set to 25 prior to configuring the gas sensor
		//* or by performing a few temperature readings without operating the gas sensor.
	//
		//*/
	gas_sensor.amb_temp = 25;


	int8_t volatile rslt = BME680_OK;
	bme680_init(&gas_sensor);




struct  bme680_field_data data;



	uint8_t set_required_settings;

	/* Set the temperature, pressure and humidity settings */
	gas_sensor.tph_sett.os_hum = BME680_OS_2X;//BME680_OS_2X;
	gas_sensor.tph_sett.os_pres = BME680_OS_4X;//BME680_OS_4X;
	gas_sensor.tph_sett.os_temp = BME680_OS_4X;//BME680_OS_4X;
	gas_sensor.tph_sett.filter = BME680_FILTER_SIZE_3;//BME680_FILTER_SIZE_3;

	/* Set the remaining gas sensor settings and link the heating profile */
	gas_sensor.gas_sett.run_gas = BME680_ENABLE_GAS_MEAS;
	/* Create a ramp heat waveform in 3 steps */
	gas_sensor.gas_sett.heatr_temp = 320; /* degree Celsius */
	gas_sensor.gas_sett.heatr_dur = 120; /* milliseconds */

	/* Select the power mode */
	/* Must be set before writing the sensor configuration */
	gas_sensor.power_mode = BME680_FORCED_MODE; //BME680_SLEEP_MODE;//

	/* Set the required sensor settings needed */
	set_required_settings = BME680_OST_SEL | BME680_OSP_SEL | BME680_OSH_SEL | BME680_FILTER_SEL
	| BME680_GAS_SENSOR_SEL;

	/* Set the desired sensor configuration */
	rslt = bme680_set_sensor_settings(set_required_settings,&gas_sensor);

	/* Set the power mode */
	rslt = bme680_set_sensor_mode(&gas_sensor);
while(1)
{
			if (bme680_ticker > 500)
			{
				bme680_ticker = 0;

				HAL_GPIO_TogglePin(LED_0_GPIO_Port, LED_0_Pin);

				rslt = bme680_get_sensor_data(&data, &gas_sensor);
				if(data.status & BME680_GASM_VALID_MSK){
				temperature = data.temperature;
				humidity = data.humidity;
				pressure = data.pressure;
				VOC = data.gas_resistance/1000; //Gasresistance in kohm
				gas_sensor.amb_temp = temperature;
				rslt = bme680_set_sensor_settings(set_required_settings,&gas_sensor);
				}

				if (gas_sensor.power_mode == BME680_FORCED_MODE) {
					rslt = bme680_set_sensor_mode(&gas_sensor);

				}
}

As I was also checking my logic analyzer, but I have no idea why it cannot find any values according to the humidity or gas_resistance.

(One while loop, he retries multiple times)

I'm thankful for any help!

Sincerely Crackl1ng

[BSTRobin · Accepted solution]

Hello Crackl1ng,

Attachement is reference code on STM32 for your reference.

[Crackl1ng]

Hello BSTRobin,

I will try it out as soon as possible! Thank you very much for the fast reply.

Edit: Thank you, worked just fine! 

[BSTRobin]

Welcome, Crackl1ng.