Hello wupengfei
Follow these connections when flashing
-> Make sure you connect RX of programmer ->TX of module and vice versa
-> VDD of module -> 3.3v ( not higher or lower )
-> GND of module -> ground
-> SPIMISO -> Ground
-> RESET -> Ground then 3.3v and then leave it on 3.3v
Also Make sure the driver for your serial programmer is installed correctly
Flashing now should succeed
after it's done make sure you return SPIMISO pin to 3.3v before doing a RESET else the code will be removed ( this might have been you're problem )
I hope this help
Let me know if it worked for you
Regards
David
