Support LSM303AGR for newer micro:bit hardware revisions

[KLOC-Karsten]

While the v1.3 of the micro:bit used the MMA8653 accelerometer, v1.5 and v2 are currently using the LSM303AGR and may use the FXOS8700 in future.

The Ada Drivers Library currently provides only the code for the MMA8653. Any application will crash when the Ada MMA8653 package is used with an v1.5 / v2 micro:bit board due to the initialization code in MicroBit.Accelerometer.

Proposed Changes

• Provide an implementation for the LSM303AGR. My implementation is available in https://github.com/KLOC-Karsten/lsm303agr
• Perhaps the MMA8653.Check_Device_Id should be handling I2C errors.
• The MicroBit.Accelerometer should autodetect the used accelerometer (see also https://github.com/KLOC-Karsten/mb_accel). The returned axis data should be independent from the used device.

[Fabien-Chouteau]

Hello @KLOC-Karsten,

A couple weeks ago I added a piece of code to detect when the expected accelerometer is not available: https://github.com/AdaCore/Ada_Drivers_Library/blob/a407ca7ddbc2d9756647016c2f8fd8ef24a239ff/boards/MicroBit/src/microbit-accelerometer.adb#L53

It would be nice indeed to have support for LSM303AGR, feel free to contribute that driver so we can integrate it in the micro:bit BSP.