Re: ESP-12 won't boot (gpioO problem?)
Posted:
Fri Jul 10, 2015 8:47 amby martinayotte
In boards.txt, there are entries like "generic.build.flash_mode=qio" or "nodemcu.build.flash_mode=qio".
So, depending of the type of flash, it could be changed to "dio".
Re: ESP-12 won't boot (gpioO problem?)
Posted:
Wed Jul 26, 2017 4:28 amby Navis-Raven
We have a similar problem here on github (
https://github.com/pfalcon/esp-open-sdk/issues/279 ) with ESP-12F (or/and ESP-12E)
It doesn't boot or it's still rebooting
Re: ESP-12 won't boot (gpioO problem?)
Posted:
Fri Aug 17, 2018 2:13 pmby mlefevre
I realize that this thread is over 3 years old but I came across it because I'm having the same problem. GPIO 0 wants to sit at 1.9v despite the pullup and the chip won't enter flash mode as a result. I'm hoping one of the original posters found the problem and can share. Could it just be defective ESP-12e modules. Both of the ones I have do this.
Re: ESP-12 won't boot (gpioO problem?)
Posted:
Mon Aug 27, 2018 10:30 pmby mlefevre
I figured out my problem. In my original design, I was not using GPIO15 and pulled it down with a 10K resistor. Later, during development, I needed another GPIO and I decided to use GPIO15 and I connected it to an existing circuit that employed a 100K pulldown resistor. I found that when GPIO15 is pulled down with only 100K, GPIO0 does not rise to 3.3v even with a 10K pullup resistor. If you change the pulldown resistor to 10K, GPIO0 rises to 3.3v. I don't know what happens on GPIO15 during boot but 100K is too large a pulldown resistor for it to work properly.