ESP8266 Community Forum

I followed the advice I found in this article. And at least once it worked fine. Then I had a fab house make a few boards and populate them and now I can't program any of them. FWIW, I measure 3.28V at RESET and GPIO2, but only 2.65V at EN. I am not sure why.

Here is the schematic.



(The ESP-12F has filter caps between 3.3V and GND so I didn't duplicate them. And anyway it worked fine without them until now.)

Any thoughts on why this doesn't work?

Remember that you need to set GPIO0 when the device boots to control the operation mode; I see you are controlling GPIO0 from the FTDI, but I do not see how are you resetting the device.

Eduperez is right ! your autoreset is attached to EN, where it should be on RES, switch those so EN will have permanent pullup, and your autoreset will pulse the RES.

Maybe you didn't read the article. The thrust of the article is that toggling RS with DTR does not always work - in fact usually doesn't with the ESP-12F devices. But toggling CH_EN instead does, which is what he shows and is what I did. And it worked at least once but not with my new boards from the fab house. And why is the voltage at EN 2.65V instead of 3.3V? Could that be related?