ESP8266 Community Forum

Posted: **Thu Mar 10, 2016 7:48 pm**

Hello,

I am trying to get GPIO0 to work as an OUTPUT for 2 hours now. I am using an ESP-01 and I know that GPIO0 is pulled up to Vcc. So when I connect an LED from Vcc (+) to GPIO0 (-) it doesn't light up for some reason. I also measured the GPIO0 voltage when it should be 0 but it stays at 3.3V no matter what I do.
I tried it with the most basic code you could think of:

Code: Select all

void setup() {
  pinMode(0, OUTPUT);
}

void loop() {
  digitalWrite(0, 0);
}

GPIO0 stays at 3.3V at all times.
I connected Vcc, CH_PD and RST directly to Vcc and GND to GND. I tried leaving Rx and Tx connected to my USB adapter and also disonnected. Same result.
What is going on here? Thanks!

Posted: **Thu Mar 10, 2016 8:23 pm**

Did you make sure of the LED polarity (anode to VCC, cathode to GPIO0 with series resistor) ?

Posted: **Thu Mar 10, 2016 9:34 pm**

Yes I did, but also when I just let GPIO0 float it should measure 0V when running my code, right? I just don’t understand the behaviour.

Posted: **Thu Mar 10, 2016 10:50 pm**

I must admit that I've never used GPIO0 to drive LED directly, but I'm using both GPIO2/GPIO0 as I2C bus in all my projects, so making GPIO0 as Output is working for sure !
Maybe you will need to check again your wiring and find the mystery there ...

ESP8266 Community Forum

Can't get GPIO0 to work as OUTPUT

Can't get GPIO0 to work as OUTPUT

Re: Can't get GPIO0 to work as OUTPUT

Re: Can't get GPIO0 to work as OUTPUT

Re: Can't get GPIO0 to work as OUTPUT