# bme680 Example implementation of BME680 software. The I2C/SPI drivers are meant to run on a Raspberry Pi 4. ![Raspberry Pi](.gitea/pi.png) Connecting the purple BME680 module board to SPI: | SPI func | BME680 Pin | Raspberry Pi Pin | | -------- | ---------- | ---------------- | | MISO | "SDO" | GPIO 9 (Pin 21) | | MOSI | "SDA" | GPIO 10 (Pin 19) | | SCLK | "SCL" | GPIO 11 (Pin 23) | | CS | "CS" | GPIO 8 (Pin 24) | ### build ```sh $ make ``` This will create demo programs `bme680_i2c` and `bme680_spi`, and logging programs `bme680_log_i2c` and `bme680_log_spi`. They all expect the pin/devices specified in `spi.c` and `i2c.c`. The loggers spit out the following every minute: ``` 2024-08-19T18:20:00+0100 22.2358 101068 65.8092 11054.4 1 ``` `Date`, `Temperature °C`, `Pressure Pa`, `% RH`, `Measured Gas resistance Ω`, `Heat stability bit` >Note: disregard measured gas resistance if the heat stability bit is not 1. ## bme680_{i2c,spi} demo output ``` par_t1: 26203 par_t2: 26519 par_t3: 3 par_p1: 35008 par_p2: -10284 par_p3: 88 par_p4: 9692 par_p5: -202 par_p6: 30 par_p7: 24 par_p8: -4 par_p9: -3469 par_p10: 30 par_h1: 794 par_h2: 1007 par_h3: 0 par_h4: 45 par_h5: 20 par_h6: 120 par_h7: -100 par_g1: 208 par_g2: 59781 par_g3: 18 range_switching_error: 19 res_heat_range: 1 res_heat_val: 46 float mode tfine: 104906.162500 temp: 20.489485 degC press: 100089.609193 Pa humidity: 64.456540 % RH gas resistance: 12100.310308 Ohm == for heater target=300.0 and ambient temp=19.0 (degC) === gas_valid_r: 1 === heat_stab_r: 1 ``` ## Burn-in / logging See file `cmd/log.c` ![Graph of gas resistance measured over time](.gitea/gas.png) ![Graph of temperature measured over time](.gitea/temp.png) ![Graph of pressure measured over time](.gitea/press.png) ![Graph of humidity measured over time](.gitea/hum.png) Compile and run ```sh $ make $ mkdir data $ stdbuf -o0 ./bme680_log_i2c 2>&1 | tee -a data/i2c.txt & $ stdbuf -o0 ./bme680_log_spi 2>&1 | tee -a data/spi.txt & # wait a couple of hours or days .. $ cd plot $ ./plot.sh ```