Here is an Arduino-compatible shield for evaluation of the Bosch Sensortec BME280 combined temperature, humidity and pressure sensor. This nice sensor intended for complicated applications can be used as a single-chip weather station.

The shield allows exercising the sensor in SPI or I2C mode simply by setting or removing a jumper. A 4-channel multiplexer in the shape of an FSAL200 makes this possible. Level shifters on all signals allow for operation of the board with both 3.3V and 5V Arduino boards.

A second jumper selects the I2C address.

The accompanying sketch detects the interface mode and selected I2C address (if applicable) and controls the sensor accordingly. Temperature, humidity and ambient air pressure data converted to standard units is output on the serial port (115200n81).

Note that after switching from SPI to I2C mode the board must be power cycled, otherwise the sensor will not recognise the change. After all other jumper setting changes the sketch must be reset.