There are several BME280 breakout boards available. Some support both SPI
and I2C, others support I2C only. Make sure that your board is SPI-capable.
This example reads temperature, humidity, and pressure from popular BME280 censor via SPI.
The code is a modified version of lukasjapan/i2c-bme280.
The diff.
Do not expect accurate readings from this example. It is made available just for demonstration purpose. It assumes data is always available. The original code is not efficient in that, some operations are performed in multiple transactions, however, the modified one uses the original as-is.
bundle exec ruby bme280.rb
The application does the followings:
- reset the device
- read censor values 10 times in a loop
Connect the FTDI board to the censor device. This example uses four-wire SPI.
Unfortunately, SPI bus lines have several aliases. Hope your board has sane silkscreen.
| FT2232 board | BME280 |
|---|---|
| ADBUS0 | SCLK/SCL |
| ADBUS1 | MOSI/SDA/SDI |
| ADBUS2 | MISO/SDO |
| ADBUS3 | CS/CSB |
> bundle exec ruby bme280.rb
T: 32.849 H: 80.027, P: 1008.13
T: 32.849 H: 57.623, P: 1008.19
T: 32.880 H: 57.500, P: 1008.16
T: 32.860 H: 57.547, P: 1008.10
T: 32.865 H: 57.629, P: 1008.16
T: 32.890 H: 57.695, P: 1008.12
T: 32.880 H: 57.559, P: 1008.13
T: 32.900 H: 57.660, P: 1008.11
T: 32.895 H: 57.701, P: 1008.10
T: 32.910 H: 57.755, P: 1008.13
This is an example to test the driver.
bundle exec ruby bme280.rb
Connect the FTDI board to the censor device just like the above example.
> bundle exec ruby bme280_simple.rb
identify chip id
reset the device
read ctrl_meas after reset
setting ctrl_meas to 0b00100101
read ctrl_meas
test successfully finished