About Ruslan

Hi. I am trying to use bme680 without BSEC library with stm32f103. I included bme api files. All things looks good but I found interesting moment that I cant understand.  For some days I recieved gas resistence from 5000 ohms to 15000 ohms. At this moment my part of source code was:   led_on; // BME680 ---------------------------------------------------------------------// bme680_port_init(); BME680_On; I2C_Port_Init(100000); // инит I2C на скорость 100 кГц delay_ms_tim(50); led_off; delay_ms_tim(450); // BME680 Sensor Initialisation gas_sensor.dev_id = 0xEC; gas_sensor.intf = BME680_I2C_INTF; gas_sensor.read = bus_read; gas_sensor.write = bus_write; gas_sensor.delay_ms = delay_ms_tim; gas_sensor.amb_temp = 25; #ifdef debug UART1_Transmit_string("\n bme680_init..."); #endif rslt = bme680_init(&gas_sensor); if (rslt != BME680_OK){ bme680_is_present = false; #ifdef debug UART1_Transmit_string("\nBME680 not found"); #endif } else{ bme680_is_present = true; #ifdef debug sprintf(uart_buf,"\nBME680 Init OK -> Chip ID 0x%x", gas_sensor.chip_id); UART1_Transmit_string(uart_buf); #endif // Set the temperature, pressure and humidity settings gas_sensor.tph_sett.os_hum = BME680_OS_1X; gas_sensor.tph_sett.os_pres = BME680_OS_16X; gas_sensor.tph_sett.os_temp = BME680_OS_2X; //gas_sensor.tph_sett.filter = 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; //gas_sensor.gas_sett.heatr_dur = 1000; // Create a ramp heat waveform in 3 steps gas_sensor.gas_sett.heatr_temp = 320; // degree Celsius gas_sensor.gas_sett.heatr_dur = 150; // milliseconds // Устанавливаем режим принудительного измерения // Must be set before writing the sensor configuration gas_sensor.power_mode = BME680_FORCED_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 profile duration //bme680_set_profile_dur(2000, &gas_sensor); // in ms // Get the profile duration of the sensor bme680_get_profile_dur(&meas_period, &gas_sensor); #ifdef debug sprintf(uart_buf,"\nBME680 profile duration: %i ms", meas_period); UART1_Transmit_string(uart_buf); #endif // Set the desired sensor configuration rslt = bme680_set_sensor_settings(set_required_settings, &gas_sensor); #ifdef debug //sprintf(uart_buf,"\nBME680 set settings -> %s", rslt ? "Error" : "Ok"); //UART1_Transmit_string(uart_buf); #endif // Set the power mode rslt = bme680_set_sensor_mode(&gas_sensor); #ifdef debug //sprintf(uart_buf,"\nBME680 set forced mode -> %s", rslt ? "Error" : "Ok"); //UART1_Transmit_string(uart_buf); #endif delay_ms_tim(meas_period); // Delay till BME680 measurement is ready rslt = bme680_get_sensor_data(&data, &gas_sensor); #ifdef debug sprintf(uart_buf,"\n\nT: %.2f degC, P: %.2f mmHg, H %.2f %%rH ", data.temperature, data.pressure / 100.0f * 75 / 100, data.humidity ); UART1_Transmit_string(uart_buf); #endif With this code I had temperature readout less than real for 1C, humidity less than real for 15%. I am using 10 sec pause with standby mode after end of measurement. Then I decided to check for what purpose function bme680_set_profile_dur(2000, &gas_sensor).  After this changing now I have at start gas resistanse 35000 ohms and 1 hour later 25000 ohms. When I comment again bme680_set_profile_dur() function I still recieve gas resistance in 25000 - 35000 range and the same unreal T and H values. Can you tell me what is real range of resistance I must recieve in typical home room and why T and H values are wrong? How oversampling and filter settings affectc on measurements? ... View more