/*
2×2 presure sensor matrix code,
where each row/column is connected to an individual analog pin
>> github plusea
*/

int rowPin1 = A2;
int rowPin2 = A3;
int colPin1 = 10;
int colPin2 = 11;
int sensorValues[] = {
0,0,0,0};

void setup() {
pinMode(rowPin1, INPUT);
pinMode(rowPin2, INPUT);
digitalWrite(16, HIGH);
digitalWrite(17, HIGH);
pinMode(colPin1, OUTPUT);
pinMode(colPin2, OUTPUT);
Serial.begin(9600);
}

void loop() {
digitalWrite(colPin1, HIGH);
digitalWrite(colPin2, LOW);
sensorValues[0] = analogRead(rowPin1);
sensorValues[1] = analogRead(rowPin2);
delay(10);
digitalWrite(colPin1, LOW);
digitalWrite(colPin2, HIGH);
sensorValues[2] = analogRead(rowPin1);
sensorValues[3] = analogRead(rowPin2);
delay(10);
Serial.print(sensorValues[0]);
Serial.print(‘,’);
Serial.print(sensorValues[1]);
Serial.print(‘,’);
Serial.print(sensorValues[2]);
Serial.print(‘,’);
Serial.print(sensorValues[3]);
Serial.println();
}

/*
Code based on Tom Igoe’s Serial Graphing Sketch
>> http://wiki.processing.org/w/Tom_Igoe_Interview

Reads 4 analog inputs and visualizes them by drawing a 2×2 grid,
using grayscale shading of each square to represent sensor value.
>> http://www.kobakant.at/DIY/?cat=347
*/

import processing.serial.*;

Serial myPort; // The serial port
int maxNumberOfSensors = 4;
float[] sensorValue = new float[maxNumberOfSensors]; // global variable for storing mapped sensor values
float[] previousValue = new float[maxNumberOfSensors]; // array of previous values
int rectSize = 200;

void setup () {
size(600, 600); // set up the window to whatever size you want
println(Serial.list()); // List all the available serial ports
String portName = Serial.list()[0];
myPort = new Serial(this, portName, 9600);
myPort.clear();
myPort.bufferUntil(‘\n’); // don’t generate a serialEvent() until you get a newline (\n) byte
background(255); // set inital background
smooth(); // turn on antialiasing
rectMode(CORNER);
}

void draw () {
fill(sensorValue[0]);
rect(width/2-rectSize, height/2-rectSize, rectSize,rectSize); //top left
fill(sensorValue[0]);
rect(width/2, height/2-rectSize, rectSize,rectSize); //top right
fill(sensorValue[0]);
rect(width/2-rectSize, height/2, rectSize,rectSize); //bottom left
fill(sensorValue[0]);
rect(width/2, height/2, rectSize,rectSize); //bottom right
}

void serialEvent (Serial myPort) {
String inString = myPort.readStringUntil(‘\n’); // get the ASCII string

if (inString != null) { // if it’s not empty
inString = trim(inString); // trim off any whitespace
int incomingValues[] = int(split(inString, “,”)); // convert to an array of ints

if (incomingValues.length <= maxNumberOfSensors && incomingValues.length > 0) {
for (int i = 0; i < incomingValues.length; i++) {
// map the incoming values (0 to 1023) to an appropriate gray-scale range (0-255):
sensorValue[i] = map(incomingValues[i], 0, 1023, 0, 255);
}
}
}
}