bme680 sensor
Rsadeika
Posts: 3,839
I got some bme680 sensors from Parallax, and they are working. The setup is: Raspberry pi 3, Adafruit bme680 driver, Python.
When I run the Python script, the temperature, humidity, pressure results are very straight forward. The problem that I am having is the results for the gas reading.
I have this setup inside the house, and the reading that I am getting is 22203 ohm. Not sure of what to do with this ohm reading. The chart that Adafruit provides does not show anything that is in ohm results. Since I am not a hardware guy, not sure what to do with these results.
Anybody solve this problem? Thanks in advance for any information.
Ray
Comments
Section 4 of the datasheet talks about employing BSEC software to manage the continuous calibration sequence that then converts from resistance to air quality index and others. The link in the datasheet is dead but this one with email request exists - https://www.bosch-sensortec.com/software-tools/software/bme688-software/
You can also run this sensor on the P2 using the BME68X driver from Bosch.
Works right out of the box.
/** * @brief BME68x Environmental Sensor * @author Michael Burmeister * @date December 7, 2019 * @version 1.0 * */ //#define DEBUG //#define BME68X_DO_NOT_USE_FPU #include <stdio.h> #include <propeller.h> #include "simpletools.h" #include "i2c.h" #include "bme68x.h" #define SAMPLE_COUNT UINT16_C(30) #define BMESCL 36 #define BMESDA 37 i2c_t *Bme; char bmemode; int main() { uint8_t dev_addr; uint16_t sample_count = 1; uint32_t del_period; /* Heater temperature in degree Celsius */ uint16_t temp_prof[10] = { 100, 100, 200, 200, 200, 200, 320, 320, 320, 320 }; /* Heating duration in milliseconds */ uint16_t dur_prof[10] = { 280, 5740, 280, 1960, 1960, 1960, 280, 1960, 1960, 1960 }; printf("Starting\n"); Bme = I2C_Init(BMESCL, BMESDA, I2C_STD); //bmemode = BME68X_SEQUENTIAL_MODE; bmemode = BME68X_FORCED_MODE; struct bme68x_dev gas_sensor; struct bme68x_conf conf; struct bme68x_heatr_conf heatr_conf; struct bme68x_data data[3]; uint32_t time_ms = 0; uint8_t n_fields; int ct; dev_addr = BME68X_I2C_ADDR_HIGH; gas_sensor.variant_id = BME68X_VARIANT_GAS_LOW; gas_sensor.intf = BME68X_I2C_INTF; gas_sensor.read = BME68xRead; gas_sensor.write = BME68xWrite; gas_sensor.delay_us = BME68xWait; gas_sensor.amb_temp = 25; gas_sensor.intf_ptr = &dev_addr; int8_t rslt = BME68X_OK; rslt = bme68x_init(&gas_sensor); printf("Results: %d\n", rslt); uint8_t set_required_settings; /* Set the temperature, pressure and humidity settings */ conf.os_hum = BME68X_OS_16X; conf.os_pres = BME68X_OS_1X; conf.os_temp = BME68X_OS_2X; conf.filter = BME68X_FILTER_OFF; conf.odr = BME68X_ODR_NONE; rslt = bme68x_set_conf(&conf, &gas_sensor); /* Set the remaining gas sensor settings and link the heating profile */ heatr_conf.enable = BME68X_ENABLE; /* Create a ramp heat waveform in 3 steps */ heatr_conf.heatr_temp = 300; /* degree Celsius */ heatr_conf.heatr_dur = 100; /* milliseconds */ heatr_conf.heatr_temp_prof = temp_prof; heatr_conf.heatr_dur_prof = dur_prof; heatr_conf.profile_len = 10; rslt = bme68x_set_heatr_conf(bmemode, &heatr_conf, &gas_sensor); printf("Config Results: %d\n", rslt); /* Trigger the next measurement if you would like to read data out continuously */ rslt = bme68x_set_op_mode(bmemode, &gas_sensor); printf("Sample, TimeStamp(ms), Temp(deg C), Pressure(Pa), Humidity(%%), Gas resistance(ohm), Status, Gas Index, Index\n"); ct = _getms(); while(sample_count < SAMPLE_COUNT) { /* Trigger the next measurement if you would like to read data out continuously */ if (bmemode == BME68X_FORCED_MODE) rslt = bme68x_set_op_mode(bmemode, &gas_sensor); del_period = bme68x_get_meas_dur(bmemode, &conf, &gas_sensor) + (heatr_conf.heatr_dur * 1000); gas_sensor.delay_us(del_period, gas_sensor.intf_ptr); time_ms = _getms(); rslt = bme68x_get_data(bmemode, &data, &n_fields, &gas_sensor); for (int i = 0;i<n_fields;i++) { printf("%6u, %13lu, %11.2f, %12.2f, %11.2f, %19.2f, %6x, %10d, %4d\n", sample_count, time_ms, data[i].temperature / 1.0f, data[i].pressure/3386.4, data[i].humidity / 1.0f, data[i].gas_resistance, data[i].status, data[i].gas_index, data[i].meas_index); sample_count++; } } while(1) { _waitms(1000); } } uint8_t BME68xRead(uint8_t reg_addr, uint8_t *data, uint16_t len, void *intf_ptr) { int i; uint8_t dev_addr = *(uint8_t*)intf_ptr; i = I2C_In(Bme, dev_addr, reg_addr, 1, data, len); #ifdef DEBUG printf("Read> i:%d, addr: %x, reg:%x, Len:%d, (%x)", i, dev_addr, reg_addr, len, data[0]); for (int j=1;j<len;j++) printf(", (%x)", data[j]); printf("\n"); #endif if (i > 0) return 0; else return -1; } uint8_t BME68xWrite(uint8_t reg_addr, uint8_t *data, uint16_t len, void *intf_ptr) { int i; uint8_t dev_addr = *(uint8_t*)intf_ptr; i = I2C_Out(Bme, dev_addr, reg_addr, 1, data, len); #ifdef DEBUG printf("Write> i:%d, id:%x, reg:%x, len:%d\n", i, dev_addr, reg_addr, len); #endif if (i > 0) return 0; else return -1; } void BME68xWait(uint32_t period, void *intf_ptr) { _waitus(period); }Ops, you may have an issue with the I2C driver on the P2 for C code. I use my own I2C driver.
Mike
Thanks. I have not fully looked into evanh suggestion. That lead, requests an email to get the necessary library file. Not sure if I will get what I need.
I have looked into a P2 suggestion, ran into multiple problems.
What I want to do is put together the cheapest plug and play solution for an outdoor thermometer assy. So far, using a raspberry Pi 3 or maybe a raspberry pi 4, seems to be cheapest and relatively reliable solution. Since I do a lot of data logging, using some kind of software socket code, has to be available. Plus having some kind of battery backup for the assy would be beneficial.
I already ordered some more bme680 sensors from Parallax, at $15, I might have to order some more, hope the sale lasts a little bit longer.
Now that I am thinking about it, getting the gas thing functional, for the bme680, would be a useful piece of data to log. Would be nice to know the quality of the outside air.
Ray