ʾʹõԴ
USER_BUTTON    -----   PB2

ʾḶ́
1ϵϵͳʱԴΪRCH48MHz
2USERʼ
3ȴûUSER
4Flashѡֽڽ
5ѡֽڲ
6жѡֽOPTR1NRST_SWD_MODEλֵ
     - NRST_SWD_MODE = 0b'00ΪNRST_SWD_MODE = 0b'10PC0λͷǰΪGPIO
     - NRST_SWD_MODE = 0b'10ΪNRST_SWD_MODE = 0b'00PC0λͷǰΪNRST

