introduce about UART




File list:
uart1
....\example.as
....\example.cof
....\example.hex
....\example.hxl
....\example.lst
....\example.map
....\example.mcp
....\example.mcs
....\example.mcw
....\example.obj
....\example.rlf
....\example.sdb
....\example.sym
....\funclist
....\main.c
....\main.dep
....\main.p1
....\main.pre
....\startup.as
....\startup.lst
....\startup.obj
....\startup.rlf
....\uart.c
....\uart.dep
....\uart.h
....\uart.p1
....\uart.pre