I'm gonna go a bit over my head with this project but it has to be done, so any help would be appreciated. I'm planning to make a project based on this one. I need to make a 8x5 array of 40 squares of velostat sensors. The player needs to go from the bottom to the top of the array in a predetermined path 18 steps + surrounding squares reset the progress which amount to about 30 sensors. Whats the easiest way of accomplishing this? Arduino mega and a digital pin for each of the sensors? They don't need to sensor pressure levels just on/off.
This kind of looks like a 8x5 keyboard matrix. So you could use 8 pins for columns and 5 for rows = 13 pins. Might reduce the number of pins further with shift registers (SPI) or I2C expanders.
Hmmm - sounds like that scene from "Raiders of the Lost Ark" 
gpsmikey:
Hmmm - sounds like that scene from "Raiders of the Lost Ark"
Something similar but less dangerous as there are no chasms in the plan; yet.
groundfungus:
This kind of looks like a 8x5 keyboard matrix. So you could use 8 pins for columns and 5 for rows = 13 pins. Might reduce the number of pins further with shift registers (SPI) or I2C expanders.
I already have a mega i thought of using for this, so number of pins are not a major problem unless this simplifies the project. The author of that project used nanos and 8 analog pins for 8 sensor pads for detecting pressure levels which i don't need. There is a fritzing breadboard schematic at the bottom of that page i'm trying to figure out.
Where do I start with coding this?
So, I found instructable for O-Mat which is basically the thing I am making but much smaller in size. Instead of making many individual sensors they have a 15x15 matrix grid for a promini and multiplexers. There is a code for this project. Could I use it as a starting point for my thing?
//Mux control pins for analog signal (SIG_pin) default for arduino mini pro
const byte s0 = 13;
const byte s1 = 12;
const byte s2 = 11;
const byte s3 = 10;
//Mux control pins for Output signal (OUT_pin) default for arduino mini pro
const byte w0 = 9;
const byte w1 = 8;
const byte w2 = 7;
const byte w3 = 6;
//Mux in "SIG" pin default for arduino mini pro
const byte SIG_pin = 0;
//Mux out "SIG" pin default for arduino mini pro
const byte OUT_pin = 5;
//Row and Column pins default for arduino mini pro
const byte STATUS_pin = 3;
const byte COL_pin = 2;
const boolean muxChannel[16][4]={
{0,0,0,0}, //channel 0
{1,0,0,0}, //channel 1
{0,1,0,0}, //channel 2
{1,1,0,0}, //channel 3
{0,0,1,0}, //channel 4
{1,0,1,0}, //channel 5
{0,1,1,0}, //channel 6
{1,1,1,0}, //channel 7
{0,0,0,1}, //channel 8
{1,0,0,1}, //channel 9
{0,1,0,1}, //channel 10
{1,1,0,1}, //channel 11
{0,0,1,1}, //channel 12
{1,0,1,1}, //channel 13
{0,1,1,1}, //channel 14
{1,1,1,1} //channel 15
};
//incoming serial byte
int inByte = 0;
int valor = 0; //variable for sending bytes to processing
int calibra[15][15]; //Calibration array for the min values of each od the 225 sensors.
int minsensor=254; //Variable for staring the min array
int multiplier = 254;
int pastmatrix[15][15];
void setup(){
pinMode(s0, OUTPUT);
pinMode(s1, OUTPUT);
pinMode(s2, OUTPUT);
pinMode(s3, OUTPUT);
pinMode(w0, OUTPUT);
pinMode(w1, OUTPUT);
pinMode(w2, OUTPUT);
pinMode(w3, OUTPUT);
pinMode(OUT_pin, OUTPUT);
pinMode(STATUS_pin, OUTPUT);
pinMode(COL_pin, OUTPUT);
digitalWrite(s0, LOW);
digitalWrite(s1, LOW);
digitalWrite(s2, LOW);
digitalWrite(s3, LOW);
digitalWrite(w0, LOW);
digitalWrite(w1, LOW);
digitalWrite(w2, LOW);
digitalWrite(w3, LOW);
digitalWrite(OUT_pin, HIGH);
digitalWrite(STATUS_pin, HIGH);
digitalWrite(COL_pin, HIGH);
Serial.begin(115200);
Serial.println("\n\Calibrating...\n");
// Full of 0's of initial matrix
for(byte j = 0; j < 15; j ++){
writeMux(j);
for(byte i = 0; i < 15; i ++)
calibra[j][i] = 0;
}
// Calibration
for(byte k = 0; k < 50; k++){
for(byte j = 0; j < 15; j ++){
writeMux(j);
for(byte i = 0; i < 15; i ++)
calibra[j][i] = calibra[j][i] + readMux(i);
}
}
//Print averages
for(byte j = 0; j < 15; j ++){
writeMux(j);
for(byte i = 0; i < 15; i ++){
calibra[j][i] = calibra[j][i]/50;
if(calibra[j][i] < minsensor)
minsensor = calibra[j][i];
Serial.print(calibra[j][i]);
Serial.print("\t");
}
Serial.println();
}
Serial.println();
Serial.print("Minimum Value: ");
Serial.println(minsensor);
Serial.println();
establishContact();
digitalWrite(COL_pin, LOW);
}
void loop(){
//Loop through and read all 16 values
//Reports back Value at channel 6 is: 346
if (Serial.available() > 0){
inByte = Serial.read();
if(inByte == 'A'){
for(int j = 14; j >= 0; j--){
writeMux(j);
for(int i = 0; i < 15; i++){
valor = readMux(i);
//Saturation sensors
int limsup = 450;
if(valor > limsup)
valor = limsup;
if(valor < calibra[j][i])
valor = calibra[j][i];
valor = map(valor,minsensor, limsup,1,254);
if(valor < 150)
valor = 0;
if(valor > 254)
valor = 254;
Serial.write(valor);
digitalWrite(COL_pin,!digitalRead(COL_pin));
}
}
}
}
}
int readMux(byte channel){
byte controlPin[] = {s0, s1, s2, s3};
//loop through the 4 sig
for(int i = 0; i < 4; i ++){
digitalWrite(controlPin[i], muxChannel[channel][i]);
}
//read the value at the SIG pin
int val = analogRead(SIG_pin);
//return the value
return val;
}
void writeMux(byte channel){
byte controlPin[] = {w0, w1, w2, w3};
//loop through the 4 sig
for(byte i = 0; i < 4; i ++){
digitalWrite(controlPin[i], muxChannel[channel][i]);
}
}
void establishContact() {
while (Serial.available() <= 0) {
Serial.print('A'); // send a capital A
delay(300);
}
}