ESP8266 Community Forum

- Tue Jul 05, 2016 4:08 am #50223

I tried with
pinMode(GPIO12, INPUT_PULLUP);
but it does not boot anymore

I tried to flash same code again with INPUT_PULLUP and it's working now!!!
Aren't there known problems with flashing tool ???

- Sat Sep 03, 2016 9:28 am #54370 Even though my board is a nodeMCU 1.0 I am programming my ESP8266 via the Arduino IDE 1.6.10 (I can also use platformIO as an IDE).

I am trying to use the internal pullup on various pins (D8 D4 etc) without any success. I am modifying the standard Blink program to add the following line to setup()

pinMode(D8,INPUT_PULLUP);

alternatively I also tried
pinMode(D8,INPUT);
digitalWrite(D8,true);

Then in the loop() I add:
Serial.println(digitalRead(D8));

What I see is generally a set of zeros. If I connect something to the input then I can make the input either a 1 or a 0 so it's working as an input. But the pullup is not working.

Googling I see discussions of, at one time, INPUT_PULLUP not working and then some fellow named zeroday fixing it so it did work. But all these discussions seemed to be about nodeLua so I don't know if they apply to programming in Ardunio IDE. The Arduino website also says PULLUP should work,

Anyhow I'm posting this in sept 2016. Surely this should be working??? I have two different boards and both behave the same and all the pins i've tried act similarly.

- Sat Sep 03, 2016 10:28 am #54375 Since GPIO15 (D8) is used by the boot mode process, most of the boards have this pin pulled down by an external resistor, which is stronger than internal weak pullup.