Baremetal firmare code pushed here was written by me back in 2014.

The sensor is not in the existence, so this code is pushed for the reference.

It is the firmware written over AVR-ATMEGA family. A reader or visitor of the repository can get following insgits looking at it -
1> Cascaded design of the firmware (HAL layer at bottom -> Driver level at middle -> Super-loop (main.c) at top dealing with middle layer
2> Writing of Baremetal driver for - I2C, UART, SPI
3> Communication driver of TI's CC2520 and CC1125
4> Coding practices to write a professional code