ʾʹõԴ
USER BUTTON  ---   PB2
LED          ---   PB1


ʾḶ́
1ϵʱӡΪEXTIģʽ¼ѣ
2ȴ3s
3DeepstopģʽWFE; ʱ¼Deepstop
4ѺָϵͳʱãͬʱLEDGPIO