QEI Feedback is ok, Vexta Feedback is ok, USART is ok.
Work to be done. Wrapper for higher level function.

Signed-off-by: ccheonglee <ccheonglee@gmail.com>
Support Step function, Home function, serial communication to PC is ok. To be done: Command list to be received and executed

Signed-off-by: ccheonglee <ccheonglee@gmail.com>