Tutorial — reading a BME280 over I²C

Prerequisites: RPBridge plugged in, driver loaded, BME280 on a Qwiic cable.

1. Confirm the adapter

i2cdetect -l | grep rpbridge
# → i2c-7  i2c  rpbridge-i2c  I²C adapter

2. Scan the bus

i2cdetect -y 7
#      0  1  2  ...  75 76 77
# 00:    -- -- ...
# 70: -- -- -- -- -- -- 76 --     ← BME280 answering on 0x76

3. Attach the kernel client driver

sudo modprobe bmp280_i2c
echo bme280 0x76 | sudo tee /sys/bus/i2c/devices/i2c-7/new_device

The IIO device iio:device0 appears.

4. Read temperature, humidity, pressure

cat /sys/bus/iio/devices/iio:device0/in_temp_input
# 24310       ← 24.310 °C

cat /sys/bus/iio/devices/iio:device0/in_humidityrelative_input
# 42350       ← 42.35 % RH

cat /sys/bus/iio/devices/iio:device0/in_pressure_input
# 1013250     ← 101.325 kPa

5. Automate with iio_readdev

iio_readdev -b 256 iio:device0 temp humidityrelative pressure > samples.raw

Pipe into Grafana's IIO plugin for a live dashboard.

Device-tree auto-provisioning

If the RPBridge dongle has the BME280 fixed on its own PCB (not a pluggable Qwiic accessory), the firmware can ship a pre-baked DT overlay that the kernel driver applies at bind time — the new_device step disappears. See dts/overlays/ for examples.