See the top level README for information on where to find the schematic and programmers reference manual for the ARM processor on the raspberry pi. Also find information on how to load and run these programs. Based on uart02, the difference is that this is primarily thumb code instead of ARM. ARM in this case meaning the traditional 32 bit instruction set and thumb meaning the traditional 16 bit instruction subset. Thumb2 has confused/blurred those definitions though. (thumb2 is a mostly 32 bit extension to the thumb instruction set using formerly undefined instructions to create variable word length instructions). From the top level readme we see that the RPi2 uses a different base address for the peripherals. Uncomment the correct line at the top of the uart03.c file depending on the Raspberry Pi you are using. See the top level README for information on how to connect the raspi uart to your host computer.