[Answered] Meaning of GPIO_PULLUP_PULLDOWN

[kolban]

Looking at the GPIO API I see a function called gpio_set_pull_mode(). I'm wondering how to describe this function. For input, I can imagine no signal (floating input) being treated as high with "pull up" and low with "pull down". What then does the option GPIO_PULLUP_PULLDOWN mean?

Does this function have any semantics for GPIO pins flagged as "output"?

[kolban]

*bump*

[ESP_Angus]

This took me a moment to understand as well, had to check with coworkers. Setting GPIO_PULLUP_PULLDOWN turns on both pull-up and pull-down resistors, which pulls the pin voltage to approximately VCC/2.

Not useful for digital GPIO functions, but you can use this to bias the input when sampling an analog signal.