/*
Pressure Sensor Matrix Code
parsing through a pressure sensor matrix grid by switching individual
rows/columns to be HIGH, LOW or INPUT (high impedance) to detect
location and pressure.
>> https://www.kobakant.at/DIY/?p=7443
*/

#define numRows 3
#define numCols 3
#define sensorPoints numRows*numCols

int rows[] = {A0, A1, A2};
int cols[] = {5,6,7};
int incomingValues[sensorPoints] = {};

void setup() {
// set all rows and columns to INPUT (high impedance):
for (int i = 0; i < numRows; i++) {
pinMode(rows[i], INPUT_PULLUP);
}
for (int i = 0; i < numCols; i++) {
pinMode(cols[i], INPUT);
}
Serial.begin(9600);
}

void loop() {
for (int colCount = 0; colCount < numCols; colCount++) {
pinMode(cols[colCount], OUTPUT); // set as OUTPUT
digitalWrite(cols[colCount], LOW); // set LOW

for (int rowCount = 0; rowCount < numRows; rowCount++) {
incomingValues[colCount * numRows + rowCount] = analogRead(rows[rowCount]); // read INPUT
}// end rowCount

pinMode(cols[colCount], INPUT); // set back to INPUT!

}// end colCount

// Print the incoming values of the grid:
for (int i = 0; i < sensorPoints; i++) {
Serial.print(incomingValues[i]);
if (i < sensorPoints – 1) Serial.print(“\t”);
}
Serial.println();
delay(10);
}

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

Reads X analog inputs and visualizes them by drawing a grid
using grayscale shading of each square to represent sensor value.
>> http://howtogetwhatyouwant.at/
*/

import processing.serial.*;

Serial myPort; // The serial port
int rows = 10;
int cols = 10;
int maxNumberOfSensors = rows*cols;
float[] sensorValue = new float[maxNumberOfSensors]; // global variable for storing mapped sensor values
float[] previousValue = new float[maxNumberOfSensors]; // array of previous values
int rectSize = 0;
int rectY;
void setup () {
size(600, 600); // set up the window to whatever size you want
rectSize = width/rows;

println(Serial.list()); // List all the available serial ports
String portName = Serial.list()[1]; // set the number of your serial port!
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 () {
for (int i = 0; i < maxNumberOfSensors; i++) {
fill(sensorValue[i]);
rect(rectSize * (i%rows), rectY, rectSize, rectSize); //top left
if((i+1) % rows == 0) rectY += rectSize;
}
rectY=0;
}

void serialEvent (Serial myPort) {
String inString = myPort.readStringUntil(‘\n’); // get the ASCII string
println(“test”);
if (inString != null) { // if it’s not empty
inString = trim(inString); // trim off any whitespace
int incomingValues[] = int(split(inString, “\t”)); // 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); // stretch 5×5
println(sensorValue[i]); // print value to see
}
}
}
}