Serial communication between Arduino and Processing

This article briefly describes the serial communication between processing and Arduino boards. The processing has many applications using Arduino serial communication, like obtaining time, sending or receiving HTTP requests, exporting or importing data, managing files, graphical or visual representation of data, UI control, etc.

Read or Write data between Processing and Arduino

Processing to Arduino

Here the processing writes the serial data and the Arduino reads it.

In the below code, the processing code generates a button on the output window. Whenever the mouse pointer is placed over that button processing writes character ‘H’ to the serial port and it changes the button color to GREEN and the text to “ON”. At the same time, when the Arduino reads an incoming serial data as character ‘H’ it turns ON the LED at digital pin 13 (LED builtin).

Similarly, on removing the pointer out of the button processing writes character ‘L’, then the LED on the Arduino turns OFF on when it receives character ‘L’ and in the window, the button color changes to RED and the text to “OFF”.

Mouse controlled LED – Processing code

import processing.serial.*;

Serial port;

void setup() {
  String portName = Serial.list()[0];
  port = new Serial(this, portName, 9600);
  size(200, 200);
}

void draw() {    
  background(255);// Background white
  // create ellipse(x,y,width,height)
  ellipse(100, 100, 50, 50);
  if ( dist( mouseX, mouseY, 100, 100 ) < 25 ) {
    port.write('H');
    fill( 0, 255, 0 );// fill green color
    text("ON", 10, 30);
  } else {
    port.write('L');
    fill( 255, 0, 0 );// fill red color
    text("OFF", 10, 30);
  }
  delay(50);
}

char state;
void setup() {
  pinMode(13, OUTPUT);
  Serial.begin(9600);
}
void loop() {
  if (Serial.available() > 0) {
    state = Serial.read();
  //  LED ON when 
    if (state == 'H') {
      digitalWrite(13, HIGH);
    }
    if (state == 'L') {
      digitalWrite(13, LOW);
    }
  }
  delay(50);
}

Arduino to Processing

Arduino Read input state code

int inputPin = 2; // Switch connected to pin 2

void setup() {
  pinMode(inputPin, INPUT);
  Serial.begin(9600); // Start serial communication at 9600 bps
}

void loop() {
  if (digitalRead(inputPin) == HIGH) {  // If switch is ON,
    Serial.write(1); // send 1 to Processing
  } else { // If the switch is not ON,
    Serial.write(0); // send 0 to Processing
  }
  delay(100); // Wait 100 milliseconds
}

Processing display input state code

Arduino and Processing communication with or without Firmata

Serial Communication between the Arduino and processing can be performed with the firmata or without firmata.

Without a firmata, the Arduino and processing will just communicate with each other and the processing will not have any Arduino control instructions. In programming without firmata, programs need to be written for both Arduino and Processing. Only serial communication will be performed between the Arduino and processing.

The above Arduino and processing codes are without firmata.