- Processing
- p5.js
- Processing.py
- Processing for Android
- Processing for Pi

- Processing Foundation

This reference is for Processing 3.0+. If you have a previous version, use the reference included with your software in the Help menu. If you see any errors or have suggestions, please let us know. If you prefer a more technical reference, visit the Processing Core Javadoc and Libraries Javadoc.

Class | GPIO
Name | ### digitalRead()
Examples |
    import processing.io.*;

    // On the Raspberry Pi GPIO 4 is physical pin 7 on the header

    void setup() {
      // INPUT_PULLUP enables the built-in pull-up resistor for this pin
      // left alone, the pin will read as HIGH
      // connected to ground (via e.g. a button or switch) it will read LOW
      GPIO.pinMode(4, GPIO.INPUT_PULLUP);
    }

    void draw() {
      if (GPIO.digitalRead(4) == GPIO.LOW) {
        // button is pressed
        fill(255);
      } else {
        // button is not pressed
        fill(204);
      }
      stroke(255);
      ellipse(width/2, height/2, width*0.75, height*0.75);
    }
Description | Returns the value of an input pin, which is either GPIO.HIGH (1) or GPIO.LOW (0) You need to set the pin to input by calling pinMode() before calling this function.
Syntax |
    .digitalRead(pin)
Parameters |
pin | int: GPIO pin
Returns | int

Updated on July 4, 2018 11:56:46am EDT