RT-Thread/rt-thread: https://github.com/RT-Thread/rt-thread.git @ a22decb71ba92fdd879914be50809c97f0defb07

guozhanxin a22decb71b 【优化】在代码中移除 rt_system_object_init/rt_system_tick_init 的调用。		%!s(int64=5) %!d(string=hai) anos
..
applications	a22decb71b 【优化】在代码中移除 rt_system_object_init/rt_system_tick_init 的调用。	%!s(int64=5) %!d(string=hai) anos
asflib_config	189c999f8e add atmel SAM D21 bsp support	%!s(int64=8) %!d(string=hai) anos
board	189c999f8e add atmel SAM D21 bsp support	%!s(int64=8) %!d(string=hai) anos
sam_d2x_asflib	62058e18fe [bsp][samd21] update scons script.	%!s(int64=7) %!d(string=hai) anos
README.txt	84f0d9f988 Update README.txt	%!s(int64=8) %!d(string=hai) anos
SAM_D2X_RTT.sct	5b1235f5f5 add scons cmd build	%!s(int64=8) %!d(string=hai) anos
SConscript	189c999f8e add atmel SAM D21 bsp support	%!s(int64=8) %!d(string=hai) anos
SConstruct	7be06b67bb [add] default environment	%!s(int64=6) %!d(string=hai) anos
project.uvprojx	0f3563fd64 [BSP] Update project files	%!s(int64=8) %!d(string=hai) anos
rtconfig.h	0d7ba79219 Remove the DBG_COLOR and DBG_ENABLE definition.	%!s(int64=6) %!d(string=hai) anos
rtconfig.py	62058e18fe [bsp][samd21] update scons script.	%!s(int64=7) %!d(string=hai) anos
template.uvprojx	189c999f8e add atmel SAM D21 bsp support	%!s(int64=8) %!d(string=hai) anos

		
				README.txt
			
				使用SAMD21-Xplained-Pro开发板
scons:
  scons
  scons --target=mdk5
demo代码演示了串口、外部中断、RTC低功耗唤醒