ESP8266 Community Forum

- Sun Dec 14, 2014 5:57 pm #4820 Hi,

Does anyone know what pulling GPIO2 low during boot actually does?

It seems to cause the chip to send loads of data to the Uart (serial), which is either some sort of connection message or its debug, as it seems to send it over and over again.

I was hoping to use GPIO2 low during restart to trigger my code to go into debug mode, but this doesnt look like its going to be possible, I'll need to wait for my ESP03 and ESP12 modules to arrive where I have access to more pins, or attempt to solder to another, which is not easy

- Sun Jan 25, 2015 12:31 am #8134 I have a similar issue, any way to stop this from happening on an 01, in my situation sometimes gpio 2 will be low on boot, help,,,


Thanks

- Sun Jan 25, 2015 1:20 pm #8186

gpio 2 will be low on boot, help,,,

GPIO 2 must not be low on boot. There is no way around this.

The chip boots in different modes depending on several of the pins:

UOTXD,MTDO,GPIO0,GPIO2 affect the boot-mode.

I believe that GPIO2 becomes an alternate UART TXD if you hold it down during boot. (don't hold me to this

Better to use a board that has more pins so you can use a different GPIO input if you need it to be in a certain state at boot time.

http://g-lab.ca/esp8266ex-gpio-registers/ might be helpful.

https://github.com/esp8266/esp8266-wiki ... ot-Process also

ESP8266 for dummies, LuaLoader and project updates: http://benlo.com/esp8266