ESP8266 Community Forum

While doing some testing I removed the already programmed ESP-12 module from WeMos D1 board and decided to try it under UNO board. The 8266 has been previously programmed with WiFiScan sketch and it was working without any problems. So I connected the ESP-12 to UNO via 5V-to-3.3V level shifters including a separate 3.3V power supply.

So far so good and the Serial Monitor was happy to report the surrounding WiFi environment as expected.

Now, I wanted to upload the very same sketch again but this time from inside UNO board.... but it did NOT work. I tried GPIO0 to GND - no difference.

What am I missing and why it does not allow me program the ESP-12 straight from arduino UNO?

Why on earth would you want to do that?

I think you may be better served on the Arduino forum and not ESP8266!

The only reason was to take advantage of arduino's USB interface as I do not have a 3.3V version of the same.