My wife was telling me the other day that, what she missed the times she played checkers with her father. And she missed playing checkers. We don't own a checkers game. So, being the geek that I am, I've decided to build one, but interactive.

Once a piece is detected on the board, a LED will light up. Neat.

This will be a log of the progress of the work

Materials needed:

  • 68 IR Leds
  • 68 Photoresistors
  • 8x 1 ohm resistors for the IR Leds lines (or columns)
  • 68x 10k ohm resistors for the Photoresistors
  • 1x black Kapaline foam board
  • wood for the case
  • black tinted 3mm glass for the top

First, how to wire a IR Photodiode and IR Led to detect an ob ject. The following Fritzing sketch will help.

The IR LED is the clear one (the emitter) and the IR Photodiode (the detector) is the black one.

The schematic is self explanatory.  Just read the analog values from A0. hover your hand above the IR emitter and detector and watch the values change.

const int analogInPin = A0;  // Analog input pin that the receiver is attached to

int sensorValue = 0;        // value read from the receiver

void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600);
  //initialize the indicator LED:
  pinMode(13, OUTPUT);
}

void loop() {
  // read the analog in value:
  sensorValue = analogRead(analogInPin);

  // print the results to the serial monitor:
  Serial.print("\nsensor = ");
  Serial.print(sensorValue);
  //the threshold found fron analog In Out program was when object is detected, the sensor value is below 100
  //set the threshold whihc you get
  //the threshold varies for different sets of emitter-receiver pairs
  if(sensorValue < 600){ //checks if object is there or not
    digitalWrite(13, HIGH);
    Serial.print("\nObject Detected");
    }
  else{
    digitalWrite(13, LOW);
    Serial.print("\nNo object in Front");
    }
  delay(500);
}

You can change the sensor value threshold .

Now, let's scale this to 8 rows x 8 columns .

According to this website, to be able to use a small amount of cables and to facilitate the connections, with a input of 12v, I can create 8 lines of 8 IR LEDs in series, each with 1 ohm resistor

The IR detectors will be connected the same, 5v with 10K resistors.

The IR LEDs and Photoresistors are from Banggood (no affiliate links)

The project size will be 36cmx36cm, divided in 8 rows x 8 columns

The Kapaline foam board is cut and the rows and columns are drawn. I've decided to create squares of 4cm each - not to small, not to big - and the checkers wood pieces i've bought are 32mm in diameter - the perfect size.

Kapaline foam with all the squares

Now, it's time to place the IR LEDs and Photoresistors

For each square, a IR LED, and a Photoresistor.

The IR LEDs are wired in series. The following picture shows this:

  • Green is 12v (connecting the LED IR in series)
  • Red is 5v (Connect the IR detectors - photoreceivers)
  • Blue is GND (black wouldn't be so perceived in this picture)