ESP8266 Community Forum

- Tue Jun 09, 2015 4:05 pm #19969 Hi all i have an issue that i don't quite understand.

I have a version 1 board and so only 2 GPIO outputs 0 and 2. I was hoping to use GPIO2 to control a device but on power up any time i connect anything to the GPIO2 pin the boards blue light is solidly on and it wont boot properly. I know its not a board issue as i have two and they both do it.


So background of my project first first im trying to make an internet of things device namely a wifi light switch. The GPIO2pin is connected via a resistor to the base of a transistor which is switching on and off a 12V relay.

thanks in advance for any help

- Tue Jun 09, 2015 4:52 pm #19977 To boot properly, both GPIO0 and GPIO2 need to be pulled-up to VCC ...
https://github.com/esp8266/esp8266-wiki ... ot-Process

- Tue Jun 09, 2015 5:04 pm #19979

To boot properly, both GPIO0 and GPIO2 need to be pulled-up to VCC ...
https://github.com/esp8266/esp8266-wiki ... ot-Process

I see, any way around this for my usage? or do i need a higher version board where other GPIOs are available that dont need to be pulled up to VCC?

- Tue Jun 09, 2015 5:36 pm #19981 All ESPs have that boot process.
If your issue is that your transistor+relay need to be driven with a HIGH level, and you don't wish to have turned ON at power up, you can simply have another NPN transistor to have that signal inverted.
Of course, if you use some other kind of ESP, such ESP-07 or ESP-12, you get more GPIOs, so you can use them instead.