rcrum003 / bme680-raspberry

C Code which reads measurements of a BME680 connected to a raspberry pi.

BME680 interface with Raspberry Pi

Introduction

This program serves as a working example to read the measurements from a BME680 via the raspberry pi. Actually I wanted to read out the sensor via python, but as the driver provided by Bosch is a C file, I created this small C program to communicate to the sensor. The compile program can then be called from python.

Usage guide

Compiling the program

Download the driver for the BME680 from github. Put the file from this repository into the same directory.

As this program uses i2c-dev, check you can use i2cdetect -y 1 to verify if your I²C communication works via bus 1. You might need to adapt the code according your I²C Bus in the line g_i2cFid = open("/dev/i2c-1", O_RDWR); to g_i2cFid = open("/dev/i2c-0", O_RDWR); if bus 0 is used. Also check the I²C address of your sensor. The provided code uses BME680_I2C_ADDR_SECONDARY (0x77) as the address.

After this adaption you can compile the program with gcc bme680_main.c bme680.c -o bme680

Command line interface

The program can be called with up to three parameters. However, be aware that no special input check is implemented.

1. ./bme680: This will print three measurement results with the time of the measurement on the standard output stream. The delay between each measurement is 3 seconds.

pi@raspberrypi:~/myproject/sensors/bme680 $ ./bme680 
**** BME680 start measurements  ****
2017-10-07 19:48:18 T: 19.51 degC, P: 1013.08 hPa, H: 69.61 %rH , G: 3954 ohms
2017-10-07 19:48:21 T: 19.53 degC, P: 1013.06 hPa, H: 69.43 %rH , G: 9471 ohms
2017-10-07 19:48:24 T: 19.54 degC, P: 1013.04 hPa, H: 69.28 %rH , G: 16839 ohms
**** Measurement finished ****
pi@raspberrypi:~/myproject/sensors/bme680 $ 

2. ./bme680 5 2: The first parameter defines the delay between each measurement. The second parameter defines the number of measurements before the program is terminated.

pi@raspberrypi:~/myproject/sensors/bme680 $ ./bme680 5 2
**** BME680 start measurements  ****
2017-10-07 20:02:41 T: 19.51 degC, P: 1012.86 hPa, H: 69.87 %rH , G: 26970 ohms
2017-10-07 20:02:46 T: 19.52 degC, P: 1012.84 hPa, H: 69.71 %rH , G: 44102 ohms
**** Measurement finished ****
pi@raspberrypi:~/myproject/sensors/bme680 $ 

3. ./bme680 5 2 output.txt: You can also provide a third argument, which will be used to write the measurements into a file.

Usage within Python

If you want to use this program in python, you can simply call it with check_output.

from subprocess import check_output
out = check_output(["bme680", str(measDelay), str(nMeas)])

If any problems with concurrent I²C bus usages occur, you can check if the file ~bme680i2c.lock exists, as this is created at the start of the program and deleted shortly before termination.