REPl working on UART6 with STMHAL

stmhal/Makefile

stmhal/boards/stm32f4xx-prefix.c

stmhal/gccollect.c

stmhal/gccollect.h

stmhal/gchelper.s

stmhal/import.c

stmhal/led.c

stmhal/led.h

stmhal/lexerfatfs.c

stmhal/lexerfatfs.h

stmhal/main.c

stmhal/malloc0.c

stmhal/math.c

stmhal/mpconfigport.h

stmhal/pin.c

stmhal/pin.h

stmhal/printf.c

stmhal/pybmodule.c

stmhal/pybmodule.h

stmhal/pyexec.c