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


ʾḶ́
1ϵʱӡΪEXTIģʽ½жϣ
2LEDƣĬϨ״̬
3ȴ3s
4stopģʽWFI; ʱEXTIжϣSTOPָϵͳʱãͬʱLEDƵ