Pull-up Resistor

[mrlx]

I'd like to activate the pull-up resistor when using a pin for digital input. Is there a way to do this?

[cfbsoftware]

If you are configuring the pin for I2C the Astrobe GPIO module automatically enables the pull-up resistor for the pin. If you have the source code for the Astrobe GPIO module you can see how it is done there. Otherwise, for other GPIO pins, the relevant bit, PUE (Pull-Up Enable), is identified in the Raspberry Pi datasheet under the heading:

PADS_BANK0: GPIO0, GPIO1, …, GPIO28, GPIO29 Registers

You can download the relevant datasheets from:

RP2040:
https://datasheets.raspberrypi.com/rp20 ... asheet.pdf

RP2350:
https://datasheets.raspberrypi.com/rp23 ... asheet.pdf

The Oberon code to set this bit for either the RP2040 or RP2350 would go something like this:

Code: Select all

(* Untested example code *)
IMPORT
  GPIO, MCU, SYSTEM;
  
PROCEDURE EnablePullup(pin: GPIO.Pin);
CONST
  PAD_PUE = 3;
VAR
  pad: INTEGER;
BEGIN
  pad := MCU.PADS_BANK0_GPIO0 + (pin * 4);
  SYSTEM.PUT(pad + MCU.ASET, {PAD_PUE});
END EnablePullup;