RT-Thread/rt-thread: https://github.com/RT-Thread/rt-thread.git @ 8a3cfe09b7a56e14b3bf5dcc324f73cff93aa310

zyh ab815cf360 [Bsp][stm32h743-nucleo] fix build error with gcc		7 lat temu
..
applications	80a21100b3 remove uart rx code	8 lat temu
asflib_config	189c999f8e add atmel SAM D21 bsp support	8 lat temu
board	189c999f8e add atmel SAM D21 bsp support	8 lat temu
sam_d2x_asflib	be0c547976 remove asflib/components	8 lat temu
README.txt	84f0d9f988 Update README.txt	8 lat temu
SAM_D2X_RTT.sct	5b1235f5f5 add scons cmd build	8 lat temu
SConscript	189c999f8e add atmel SAM D21 bsp support	8 lat temu
SConstruct	189c999f8e add atmel SAM D21 bsp support	8 lat temu
project.uvprojx	0f3563fd64 [BSP] Update project files	8 lat temu
rtconfig.h	189c999f8e add atmel SAM D21 bsp support	8 lat temu
rtconfig.py	ab815cf360 [Bsp][stm32h743-nucleo] fix build error with gcc	7 lat temu
template.uvprojx	189c999f8e add atmel SAM D21 bsp support	8 lat temu

		
				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