Published December 27, 2017 © MIT

Draw with LEDs and Logic

Easily draw whatever you want on an LED matrix with just a joystick.

BeginnerFull instructions provided3 minutes1,841

Things used in this project

Hardware components

Elecrow MAX7219 8x8 Matrix Display Module - Red Dot

Elecrow Thumb joystick module

Breadboard (generic)

Software apps and online services

Arduino IDE

Story

I just had for Christmas one of the many Arduino UNO starter kits. After I went through how to use almost each component, I didn't really know what to do with them, and when I was searching suggestions online, there were no middle between super cool, long and expensive projects; and tutorials on how to light a LED.

When I had learnt how to use those two components, I thought that it would be nice to be able to directly display things without programming it; and so I came up with my joystick.

Assembly

We don't need to do any more connections than the components' ones. However, we still have to use a breadboard, as both joystick and matrix require 5V alimentation; whereas the board only has one available.

Here is the result:

1 / 2

Coding

The point of the program stands on logic: instead of creating a complicated and heavy two-dimensional array to control the whole matrix status; we're gonna simply create a boolean describing the actual "mode" (writing or erasing), and then the rest depends of it:

void loop(){
    if (writing){
        lc.setLed(0,abscissa,ordinate,true);
    }
    
    /* Joystick events ... */
    
    // blinking point
    lc.setLed(0,abscissa,ordinate,true);
    delay(delayTime1);
    lc.setLed(0,abscissa,ordinate,false);
    delay(delayTime1);
}

When the blinking point will change of abscissa and/or of ordinate - during the joystick events; the precedent place will only be lit if it was just before, and so if writing was true.

Demonstration

As you see, pressing the joystick induces changing the mode between writing and erasing. Note that the actual position will also be lit or shut off.

Conclusion

This is my first Arduino project. I wanted to show something simple that every beginner could do with his own abilities and materials, but would still be interesting to shape.

Code

Paint_source_code

/* https://www.hackster.io/projects/6248f2
 * Created by FrenchMasterSword
 * 2017.12.27
 * 
 * Allows to draw and erase linearly
 * on a MAX7219 LED matrix
 * 
 * Pin layout: component - UNO
 * ----Joystick - UNO----
 * SW - 2
 * Vry - A0
 * Vrx - A1
 * +5V - 5V
 * GND - GND
 * ----MAX7219 - UNO---
 * VCC - 5V
 * GND - GND
 * DIN - 12
 * CS - 11
 * CLK - 10
 */

#include "LedControl.h" // library to control matrix

LedControl lc=LedControl(12,10,11,1); // initialise matrix

bool writing = false;

const int SW_pin = 2; // digital pin for 'select' output
const int X_pin = 1; // analog pin for X output
const int Y_pin = 0; // analog pin for Y output

/*proportions of the matrix (from 0 to 7)*/
const int matrixSizeX = 7;
const int matrixSizeY = 7;

int abscissa = 0;
int ordinate = 0;

unsigned int delayTime1 = 500;
unsigned int delayTime2 = delayTime1/2;

void setup() {
  lc.shutdown(0, false); // wakeup call
  lc.setIntensity(0,8);
  lc.clearDisplay(0);

  pinMode(SW_pin, INPUT); // 'select' pin
  digitalWrite(SW_pin, HIGH); // 'select' is on
}

void loop() {
  /*Light the LED in writing mode*/
  if (writing){
    lc.setLed(0,abscissa,ordinate,true);
  }
  /*The joystick returns a value between 0 and 1024
  so 256 and 768 corresponds to a half leaned joystick in respective directions*/
  
  /*The way we hold the joystick is mirrored so the values mean the opposite*/
  if ((analogRead(X_pin) > 767)&&(abscissa > 0)){
    abscissa--;
  }
  if ((analogRead(X_pin) < 257)&&(abscissa < matrixSizeX)){
    abscissa++;
  }
  if ((analogRead(Y_pin) > 767)&&(ordinate < matrixSizeY)){
    ordinate++;
  }
  if ((analogRead(Y_pin) < 257)&&(ordinate > 0)){
    ordinate--;
  }

  /*The 'select' returs 1 when up ; and 0 when down*/
  if (digitalRead(SW_pin)==0){
    /*We alternate the value of writing*/
    if (writing){
      writing=false;
    }
    else{
      writing=true;
    }

    /*We signal the modification by a quicker blink*/
    lc.setLed(0,abscissa,ordinate,true);
    delay(delayTime2);  
    lc.setLed(0,abscissa,ordinate,false);
    delay(delayTime2);
  }

  /*Blinking point*/
  lc.setLed(0,abscissa,ordinate,true);
  delay(delayTime1);  
  lc.setLed(0,abscissa,ordinate,false);
  delay(delayTime1);
}

Draw with LEDs and Logic

Things used in this project

Hardware components

Software apps and online services

Story

Assembly

Coding

Demonstration

Conclusion

Schematics

Assembly

Code

Paint_source_code

Credits

FrenchMasterSword

Comments

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Draw with LEDs and Logic

Draw with LEDs and Logic

Things used in this project

Hardware components

Software apps and online services

Story

Assembly

Coding

Demonstration

Conclusion

Schematics

Assembly

Code

Paint_source_code

Credits

FrenchMasterSword

Comments

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