Serial connection of Processing and Arduino

Question

I'm trying to make a serial connection from processing to arduino. The idea is that when I press "a", the speaker from Arduino will produce a sound and the same goes with another key pressed but with a different note. However, I'm a bit stuck with the codes. Can anyone let me know what is the problem of my codes?

Processing code:

import processing.serial.*;
Serial myPort; 
int val; // Data received from the serial port

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

void draw() {
}

 void keyPressed(){
   if (key == 'a'){
     myPort.write(1); 
   }
   if (key == 'd'){
     myPort.write(2); 
   }  
 }
 void keyReleased(){
   myPort.write(0);
 }

Arduino code:

char val; // Data received from the serial port
int speakerPin = 8;

void setup() {
pinMode(speakerPin, OUTPUT);
Serial.begin(9600); 
}

void loop() {
while (Serial.available()) { 
val = Serial.read(); 
}
if (val == '1') {  
tone(speakerPin, 262, 200); 
} else if (val == '2'){
tone(speakerPin, 523, 200); 
}
delay(100); 
}

Many many thanks!

George Profenza · Accepted Answer · 2022-06-03 20:42:33Z

1

You are so close!

The issue is on the Arduino side you're checking characters, however, on the Processing side you're sending the actual values, not the ASCII characters.

1 != '1' (49)
2 != '2' (50)

In Processing, simply use the char type single quote symbols:

myPort.write('1');

...

myPort.write('2');

(which is the same as myPort.write(49); for '1', myPort.write(50); for '2')

Alternatively you can change the way you're checking on Arduino side to not use chars to be consistent with how you're sending from Processing. e.g.

if (val == 1)

(instead of if (val == '1')).

answered Jun 3, 2022 at 20:42

George Profenza

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1 Comment

mhopeng Over a year ago

Also, consider sending the character of the keyboard key that is pressed instead of translating 'a' into '1', 'b' into '2', etc. Instead, send the key character ('a'), and in the Arduino code, check for an 'a': if val=='a', etc. Then the Processing code can just be: void keyPressed(){myPort.write(key);}.

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