Digital Clock using MAX7219 LED Dot Matrix Display

Today in this video we will discuss how to make a Digital Clock using MAX7219 LED Display. This LED Display consists of Four 8*8 LED Matrix Display.

At first the HexaDecimal files comes to the Microcontroller then it comes to the Peripheral Part means to the LED Display.

Here I used D1 Mini as Microcontroller, anyone can used ESP8266 instead of D1 Mini.

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Components

(1) MAX7219 Dot Matrix MCU LED Display Control Module Kit : https://amzn.to/3V5eboN
(2) Wemos® D1 Mini NodeMcu Lua WIFI ESP8266 Development Board: https://amzn.to/41IWgXw
(3) Programming USB Cable: https://amzn.to/3Nj01yj
(4) MAX7219 Display 4 in 1 : https://amzn.to/3n3DI4Y

Circuit Diagram

Step By Step

Ok let it be simple, first glow the first LED in the first row in the first 8*8 LED Matrix.

In this way we can easily create the digit 0 by sending HexaDecimal files to the Microcontroller.

Similarly we create the array of HexaDecimals for the each digit and sending these array of HexaDecimal files to the 1st 8*8 LED Matrix.

Finally we send these array of HexaDecimals to 2nd, 3rd and 4th 8*8 LED Matrix.

We can now easily make a Digital Clock by setting the Time that after every minute 1st and 2nd 8*8 LED Matrix changes and every 60 minute Hour segment means 3rd an 4th 8*8 LED Matrix changes.

Code

#include <MD_MAX72xx.h>
#include <SPI.h>

#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
#define MAX_DEVICES 4
#define CLK_PIN   14   // or SCK  D5
#define DATA_PIN  13  // or MOSI D7
#define CS_PIN    2  // or SS   D4

MD_MAX72XX mx = MD_MAX72XX(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);   // SPI hardware interface

unsigned char setzero[8]={0x38, 0x6c, 0x6c, 0x6c, 0x6c, 0x6c, 0x6c, 0x38}; //Digit 0
unsigned char setone[8]={0x18, 0x38, 0x18, 0x18, 0x18, 0x18, 0x18, 0x7e};  //Digit 1
unsigned char settwo[8]={0x38, 0x6c, 0x0c, 0x0c, 0x38, 0x60, 0x6c, 0x7c};  //Digit 2
unsigned char setthree[8]={0x38, 0x6c, 0x0c, 0x3c, 0x0c, 0x0c, 0x6c, 0x38};//Digit 3
unsigned char setfour[8]={0x0c, 0x1c, 0x2c, 0x6c, 0x7c, 0x0c, 0x0c, 0x0c}; //Digit 4

unsigned char setfive[8]={0x7c, 0x60, 0x60, 0x78, 0x0c, 0x0c, 0x6c, 0x78}; //Digit 5
unsigned char setsix[8]={0x38, 0x6c, 0x60, 0x78, 0x6c, 0x6c, 0x6c, 0x38};  //Digit 6
unsigned char setseven[8]={0x7c, 0x7c, 0x0c, 0x18, 0x30, 0x60, 0x60, 0x60};//Digit 7
unsigned char seteight[8]={0x38, 0x6c, 0x6c, 0x38, 0x6c, 0x6c, 0x6c, 0x38};//Digit 8
unsigned char setnine[8]={0x38, 0x6c, 0x6c, 0x3c, 0x0c, 0x0c, 0x4c, 0x38}; //Digit 9

void setup() 
{
  // put your setup code here, to run once:
     mx.begin();
}

void loop() 
{
         for (int j=0; j<8; j++)
         {
          mx.setRow(i, j, setzero[j]);   // For setting Digit Zero 
         }
}

Code to Note

mx.setRow(i, j, 0x00) – In this function the parameter i is used for which LED Matrix we want to display. If we set i=0; then 1st LED Matrix will glow, if we set i=3; then 4th LED Matrix will glow. The parameter j is used for which row we want to display. If we set j=0; then in 1st row will glow, if we set j=7; then in 8th row will glow.

Result

By this program we can control any LED that we want to glow in the big 32*8 LED Display by sending array of Hexa Decimals. Similarly, we can also reprogram the ARDUINO and change the Hexa Decimals and make any kind of animations.

Further Readings

• Arduino Tutorial 5 : Serial Control 8 LED’s
• 3x3x3 Led Cube

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