Create firmware for ADXL345

[andygrillo]

Our current firmware allows an ESP32 and ADXL355 to communicate. However the ADXL355 is expensive.

The ADXL345 is readily available and very low cost. For users to get started with a very affordable sensor, perhaps simply an esp32 dev board wired to an ADXL345, we should provide an option in the firmware to replace the accelerometer.

Whilst the ADXL355 is a much better accelerometer, it shares many characteristics with the ADXL345 (FIFO size, startup routine, etc) which should make swapping it out doable.

Datasheets:

• datasheet ADXL355
• datasheet ADXL345