Re: Connectiong GPIO2 to GND on Startup results in junk in
Posted: Thu Apr 07, 2016 7:21 am
GPIO15/GPIO2/GPIO0 are special pins that dictate the way ESP is booting.
https://github.com/esp8266/esp8266-wiki ... ot-Process
So, GPIO15 needs to be pulled down while GPIO2/GPIO0 needs to be pulled up to boot in execution mode.
It has always been like that.
You can still use those pins for other purposes, but you need to take care of the states above at reset or poweron.
For example you can place an LED on GPIO15 with cathode side to GND, and keeping the pulldown, it will work.
Doing the same on GPIO2 won't work, except if you reverse it and connect cathode to GPIO2 and anode to VCC and along with the pullup.
https://github.com/esp8266/esp8266-wiki ... ot-Process
So, GPIO15 needs to be pulled down while GPIO2/GPIO0 needs to be pulled up to boot in execution mode.
It has always been like that.
You can still use those pins for other purposes, but you need to take care of the states above at reset or poweron.
For example you can place an LED on GPIO15 with cathode side to GND, and keeping the pulldown, it will work.
Doing the same on GPIO2 won't work, except if you reverse it and connect cathode to GPIO2 and anode to VCC and along with the pullup.