RT-Thread/rt-thread: https://github.com/RT-Thread/rt-thread.git @ lts-v3.1.x

Meco Man 03f4d40e30 [lts 3,1,x] format codes		%!s(int64=4) %!d(string=hai) anos
..
applications	c1ccceb0f9 Update the bsp to master v4.0.1 version.	%!s(int64=6) %!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	56075ce8a3 [bsp] sync to master version(366e28f47682f76b3f6df85c3dcbd9785a01fa39), not contain stm32 new BSP.	%!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	4875ee8a3a Sync from master (75a3f3dd3a930eab1dc58fa0258a9d1605a0ac11)	%!s(int64=6) %!d(string=hai) anos
project.uvprojx	0f3563fd64 [BSP] Update project files	%!s(int64=8) %!d(string=hai) anos
rtconfig.h	03f4d40e30 [lts 3,1,x] format codes	%!s(int64=4) %!d(string=hai) anos
rtconfig.py	56075ce8a3 [bsp] sync to master version(366e28f47682f76b3f6df85c3dcbd9785a01fa39), not contain stm32 new BSP.	%!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