E-notice board using NodeMCU ESP8266

In this tutorial, we will make a WIFI based notice board that can display text messages and can be changed at any time.

BeginnerProtip4 hours847

Things used in this project

Hardware components

NodeMCU ESP8266 Breakout Board

DIYables Jumper Wires

Maxim Integrated MAXREFDES99# MAX7219 Display Driver Shield

DIYables Breadboard

Software apps and online services

Arduino IDE

Maxim Integrated MAX7219 Dot Matrix Library

Story

In this tutorial, we will make a WIFI based notice board that can display text messages and can be changed at any time. Here we will use MAX7219 32x8 dot matrix display module to display our text message and NodeMCU as our microcontroller. In one of our tutorials on Bluetooth-based notice boards, we make use of Bluetooth to communicate wirelessly with the Arduino UNO goto project. But in this tutorial, we will use WIFI to communicate wirelessly which will give a long range of communication within the WIFI network. As this system works on the same WIFI network you may call this the disadvantage of this project.

On the other hand, if you want to make a notice board for an organization or for an institution this is the best project.

About the display: The basic display is about an 8x8 dot matrix of LED on a MAX7219 IC. But the module we are going to use is about 32 LED in columns and 8 LED in rows. So this 32x8 LED matrix is driven by 4 MAX7219 IC. Each IC is responsible to control 8x8 LED matrixes. These modules can make a daisy chain-like structure and build to a comparable size.

Display Specifications:

The Size of the display is about 128x33x15 mm.
LED Matrix contains 256 dots (32x8).
Color: RED
This can be interfaced using 3-Wire Serial Interface.
Voltage: 4.5 ~ 5v

Hardware Requirements:

NodeMCU v0.1
MAX7219 32x8 Dot matrix display.
Small breadboard
Connecting wires.

Software Requirements:

Arduino IDE (You can download it from HERE)
MAX7219 DMD Library

Block diagram:

Circuit diagram: Follow the circuit diagram and the table below and build the connection correctly. read more here

MAX7219 IC 32x8 DMD display connection with NodeMCU:

goto the full connection diagram.

Project full source code

#include <SPI.h>        //SPI.h must be included as DMD is written by SPI (the IDE complains otherwise)
#include <DMD.h>        
#include <TimerOne.h>   
#include "SystemFont5x7.h"
#include "Arial_black_16.h"
#include <SoftwareSerial.h>// import the serial library

SoftwareSerial testserial(2, 3); // RX, TX
//Fire up the DMD library as dmd
#define DISPLAYS_ACROSS 1
#define DISPLAYS_DOWN 1
DMD dmd(DISPLAYS_ACROSS, DISPLAYS_DOWN);
//number max of characters in your message
#define max_char 100
char message[max_char];    // stores you message
//char mess[max_char];
char r_char;               // reads each character
byte index = 0;            // defines the position into your array
int i;            
char greeting[] = "MyEngineeringStuffs";

void ScanDMD()
{ 
  dmd.scanDisplayBySPI();
}

void setup(void)
{

   //initialize TimerOne's interrupt/CPU usage used to scan and refresh the display
   Timer1.initialize( 5000 );           //period in microseconds to call ScanDMD. Anything longer than 5000 (5s) and you can see flicker.
   Timer1.attachInterrupt( ScanDMD );   //attach the Timer1 interrupt to ScanDMD which goes to dmd.scanDisplayBySPI()
  
   //clear/init the DMD pixels held in RAM
   dmd.clearScreen( true );   //true is normal (all pixels off), false is negative (all pixels on)
   testserial.begin(9600); //Software serial initialization
   Serial.begin(9600);
strcpy(message,greeting);
}
void loop(void)
{
   //check if serial is avaible an before reading a new message delete's the old message
    
   if(testserial.available())
   {       
        for(i=0; i<99; i++){
            message[i] = '\0';
            Serial.print(message[i]);
        } 
        //resests the index        
        index=0;
    }

    //while is reading the message 
    while(testserial.available() > 0){
       //the message can have up to 100 characters 
       dmd.clearScreen( true );
       if(index < (max_char-1)) 
       {         
           r_char = testserial.read();      // Reads a character
           message[index] = r_char;     // Stores the character in message array
           index++;                     // Increment position      
       } 
   }
    
 //prepares the display to print our message
   dmd.selectFont(Arial_Black_16);
   //displays the message
   dmd.drawMarquee(message ,max_char,(32*DISPLAYS_ACROSS)-1 ,0);
   long start=millis();
   long timer=start;
   boolean ret=false;
   while(!ret)
   {
     if ((timer+30) < millis()) {
       ret=dmd.stepMarquee(-1,0);
       timer=millis();
     }
   }
}