I used this wiring schematic for a couple of my ESP8266-12F projects for programming mode:
As I built enough confidence with the module, I decided to go ahead with a PCB design. When I try to upload a sketch, it wouldn't go into programming mode although I think my design is correct. I checked the connections between pads and headers and they all connected. Am I missing something here? Would you please check the connections and let me know of possible cause?
esptool.py v3.0 Serial port COM4' Connecting........_____....._____....._____....._____....._____....._____...._____ esptool.FatalError: Failed to connect to ESP8266: Invalid head of packet (0xE0)