The GPIO 2 and 3 pins are the I2C pins and both have 1.8 k ohm pull up resistors. Can they still be used as GPIO pins even with these resistors?

  • Don't all the pins have internal pull-ups, or am I mis-remembering? Feb 2, 2016 at 17:03
  • 1
    @PeteHooper All the GPIO have internal pull-ups/downs which can be switched on/off in software. I2C SDA/SCL, pins 3/5 additionally have hard wired 1k8 pull-ups to 3V3.
    – joan
    Feb 2, 2016 at 17:47

1 Answer 1


Yes, they can still be used as GPIO.

It's best to use something which doesn't waste the hard wired 1k8 pull-ups to 3V3. E.g. if they are used as a switch wire the switch so that it is connected between ground and the GPIO. The switch will normally read high, but will read low when closed.

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