matrix – Blog eTechPath https://blog.etechpath.com Tue, 03 Jan 2023 12:37:06 +0000 en-US hourly 1 https://wordpress.org/?v=6.5.5 https://blog.etechpath.com/wp-content/uploads/2017/08/BrandLogo12-150x150.png matrix – Blog eTechPath https://blog.etechpath.com 32 32 How to Control MAX7219 LED Matrix with ESP8266 WiFi Module https://blog.etechpath.com/how-to-control-max7219-led-matrix-with-esp8266-wifi-module/ https://blog.etechpath.com/how-to-control-max7219-led-matrix-with-esp8266-wifi-module/#comments Sat, 02 Dec 2017 00:40:20 +0000 https://blog.etechpath.com/?p=496 About this Project:
In this project we will learn how to interfacing ESP8266 module with MAX7219 matrix display to scrolling text message from web user interface. We will use Arduino IDE to program ESP module in this project. I am using MajicDesigns MD_MAX72xx library for running this project, also the code is very similar to included example in the library with some improvements in web user interface html code.




Components:

  1. MAX7219 8×8 LED Matrix
  2. ESP8266 Node MCU
  3. USB Cable for programming and power

Circuit Diagram:

Steps: 

      1. Connect the circuit as shown above.
      2. Install Arduino IDE form arduino website. After that install ESP8266 board and library in Arduino IDE.
      3. Download and install MD_MAX7219 Library from download section for driving MAX7219 matrix. For using this library you will need to edit MAX72xx.h file for configure the type of LED matrix you are using. In this project we are using FC-16 Chinese module.
      4. Download code ino file from download section and open it with Arduino IDE.
      5. You will need to edit WiFi network SSID and Password inside your code before flashing it in ESP module. 
        const char* ssid = "your SSID";                   // edit your wifi SSID here
const char* password = "your Password";            // edit your wifi password here
      6. Select board to NodeMCU and flash the code in ESP module.
      7. Power up the circuit and you will see IP address of your ESP module allocated by your WiFi network on Matrix display. (watch video)



    1. Now open that IP address in any browser connected in same network. And you will see web user interface to enter text.
    2. For detailed procedure of configuring WiFi module with your home network and using web interface, please watch embedded YouTube video linked at the bottom of this page.

Code:

//Link: https://blog.etechpath.com

#include <ESP8266WiFi.h>
#include <MD_MAX72xx.h>
#include <SPI.h>

#define	PRINT_CALLBACK	0
#define DEBUG 0
#define LED_HEARTBEAT 0

#if DEBUG
#define	PRINT(s, v)	{ Serial.print(F(s)); Serial.print(v); }
#define PRINTS(s)   { Serial.print(F(s)); }
#else
#define	PRINT(s, v)
#define PRINTS(s)
#endif

#if LED_HEARTBEAT
#define HB_LED  D2
#define HB_LED_TIME 500 // in milliseconds
#endif

#define	MAX_DEVICES	4

#define	CLK_PIN		D5 // or SCK
#define	DATA_PIN	D7 // or MOSI
#define	CS_PIN		D8 // or SS

// SPI hardware interface
//MD_MAX72XX mx = MD_MAX72XX(CS_PIN, MAX_DEVICES);
#define HARDWARE_TYPE MD_MAX72XX::PAROLA_HW  //edit this as per your LED matrix hardware type
MD_MAX72XX mx = MD_MAX72XX(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);
// Arbitrary pins
//MD_MAX72XX mx = MD_MAX72XX(DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

// WiFi login parameters - network name and password
const char* ssid = "your SSID";                   // edit your wifi SSID here
const char* password = "your Password";            // edit your wifi password here

// WiFi Server object and parameters
WiFiServer server(80);

// Global message buffers shared by Wifi and Scrolling functions
const uint8_t MESG_SIZE = 255;
const uint8_t CHAR_SPACING = 1;
const uint8_t SCROLL_DELAY = 75;

char curMessage[MESG_SIZE];
char newMessage[MESG_SIZE];
bool newMessageAvailable = false;

char WebResponse[] = "HTTP/1.1 200 OK\nContent-Type: text/html\n\n";

char WebPage[] =
"<!DOCTYPE html>" \
"<html>" \
"<head>" \
"<title>eTechPath MAX7219 ESP8266</title>" \
"<style>" \
"html, body" \ 
"{" \
"width: 600px;" \
"height: 400px;" \
"margin: 0px;" \
"border: 0px;" \
"padding: 10px;" \
"background-color: white;" \
"}" \
"#container " \
"{" \
"width: 100%;" \
"height: 100%;" \
"margin-left: 200px;" \
"border: solid 2px;" \
"padding: 10px;" \
"background-color: #b3cbf2;" \
"}" \          
"</style>"\
"<script>" \
"strLine = \"\";" \
"function SendText()" \
"{" \
"  nocache = \"/&nocache=\" + Math.random() * 1000000;" \
"  var request = new XMLHttpRequest();" \
"  strLine = \"&MSG=\" + document.getElementById(\"txt_form\").Message.value;" \
"  request.open(\"GET\", strLine + nocache, false);" \
"  request.send(null);" \
"}" \
"</script>" \
"</head>" \
"<body>" \
"<div id=\"container\">"\
"<H1><b>WiFi MAX7219 LED Matrix Display</b></H1>" \ 
"<form id=\"txt_form\" name=\"frmText\">" \
"<label>Msg:<input type=\"text\" name=\"Message\" maxlength=\"255\"></label><br><br>" \
"</form>" \
"<br>" \
"<input type=\"submit\" value=\"Send Text\" onclick=\"SendText()\">" \
"<p><b>Visit Us at</b></p>" \ 
"<a href=\"http://www.eTechPath.com\">www.eTechPath.com</a>" \
"</div>" \
"</body>" \
"</html>";

char *err2Str(wl_status_t code)
{
  switch (code)
  {
  case WL_IDLE_STATUS:    return("IDLE");           break; // WiFi is in process of changing between statuses
  case WL_NO_SSID_AVAIL:  return("NO_SSID_AVAIL");  break; // case configured SSID cannot be reached
  case WL_CONNECTED:      return("CONNECTED");      break; // successful connection is established
  case WL_CONNECT_FAILED: return("CONNECT_FAILED"); break; // password is incorrect
  case WL_DISCONNECTED:   return("CONNECT_FAILED"); break; // module is not configured in station mode
  default: return("??");
  }
}
uint8_t htoi(char c)
{
  c = toupper(c);
  if ((c >= '0') && (c <= '9')) return(c - '0');
  if ((c >= 'A') && (c <= 'F')) return(c - 'A' + 0xa);
  return(0);
}
boolean getText(char *szMesg, char *psz, uint8_t len)
{
  boolean isValid = false;  // text received flag
  char *pStart, *pEnd;      // pointer to start and end of text
  // get pointer to the beginning of the text
  pStart = strstr(szMesg, "/&MSG=");
  if (pStart != NULL)
  {
    pStart += 6;  // skip to start of data
    pEnd = strstr(pStart, "/&");
    if (pEnd != NULL)
    {
      while (pStart != pEnd)
      {
        if ((*pStart == '%') && isdigit(*(pStart+1)))
        {
          // replace %xx hex code with the ASCII character
          char c = 0;
          pStart++;
          c += (htoi(*pStart++) << 4);
          c += htoi(*pStart++);
          *psz++ = c;
        }
        else
          *psz++ = *pStart++;
      }
      *psz = '\0'; // terminate the string
      isValid = true;
    }
  }
  return(isValid);
}
void handleWiFi(void)
{
  static enum { S_IDLE, S_WAIT_CONN, S_READ, S_EXTRACT, S_RESPONSE, S_DISCONN } state = S_IDLE;
  static char szBuf[1024];
  static uint16_t idxBuf = 0;
  static WiFiClient client;
  static uint32_t timeStart;

  switch (state)
  {
  case S_IDLE:   // initialise
    PRINTS("\nS_IDLE");
    idxBuf = 0;
    state = S_WAIT_CONN;
    break;
  case S_WAIT_CONN:   // waiting for connection
    {
      client = server.available();
      if (!client) break;
      if (!client.connected()) break;
#if DEBUG
      char szTxt[20];
      sprintf(szTxt, "%03d:%03d:%03d:%03d", client.remoteIP()[0], client.remoteIP()[1], client.remoteIP()[2], client.remoteIP()[3]);
      PRINT("\nNew client @ ", szTxt);
#endif
      timeStart = millis();
      state = S_READ;
    }
    break;
  case S_READ: // get the first line of data
    PRINTS("\nS_READ");
    while (client.available())
    {
      char c = client.read();
      if ((c == '\r') || (c == '\n'))
      {
        szBuf[idxBuf] = '\0';
        client.flush();
        PRINT("\nRecv: ", szBuf);
        state = S_EXTRACT;
      }
      else
        szBuf[idxBuf++] = (char)c;
    }
    if (millis() - timeStart > 1000)
    {
      PRINTS("\nWait timeout");
      state = S_DISCONN;
    }
    break;
  case S_EXTRACT: // extract data
    PRINTS("\nS_EXTRACT");
    // Extract the string from the message if there is one
    newMessageAvailable = getText(szBuf, newMessage, MESG_SIZE);
    PRINT("\nNew Msg: ", newMessage);
    state = S_RESPONSE;
    break;
  case S_RESPONSE: // send the response to the client
    PRINTS("\nS_RESPONSE");
    // Return the response to the client (web page)
    client.print(WebResponse);
    client.print(WebPage);
    state = S_DISCONN;
    break;
  case S_DISCONN: // disconnect client
    PRINTS("\nS_DISCONN");
    client.flush();
    client.stop();
    state = S_IDLE;
    break;

  default:  state = S_IDLE;
  }
}
void scrollDataSink(uint8_t dev, MD_MAX72XX::transformType_t t, uint8_t col)
// Callback function for data that is being scrolled off the display
{
#if PRINT_CALLBACK
  Serial.print("\n cb ");
  Serial.print(dev);
  Serial.print(' ');
  Serial.print(t);
  Serial.print(' ');
  Serial.println(col);
#endif
}
uint8_t scrollDataSource(uint8_t dev, MD_MAX72XX::transformType_t t)
// Callback function for data that is required for scrolling into the display
{
  static enum { S_IDLE, S_NEXT_CHAR, S_SHOW_CHAR, S_SHOW_SPACE } state = S_IDLE;
  static char		*p;
  static uint16_t	curLen, showLen;
  static uint8_t	cBuf[8];
  uint8_t colData = 0;
  // finite state machine to control what we do on the callback
  switch (state)
  {
  case S_IDLE: // reset the message pointer and check for new message to load
    PRINTS("\nS_IDLE");
    p = curMessage;      // reset the pointer to start of message
    if (newMessageAvailable)  // there is a new message waiting
    {
      strcpy(curMessage, newMessage); // copy it in
      newMessageAvailable = false;
    }
    state = S_NEXT_CHAR;
    break;
  case S_NEXT_CHAR: // Load the next character from the font table
    PRINTS("\nS_NEXT_CHAR");
    if (*p == '\0')
      state = S_IDLE;
    else
    {
      showLen = mx.getChar(*p++, sizeof(cBuf) / sizeof(cBuf[0]), cBuf);
      curLen = 0;
      state = S_SHOW_CHAR;
    }
    break;
  case S_SHOW_CHAR:	// display the next part of the character
    PRINTS("\nS_SHOW_CHAR");
    colData = cBuf[curLen++];
    if (curLen < showLen)
      break;
    // set up the inter character spacing
    showLen = (*p != '\0' ? CHAR_SPACING : (MAX_DEVICES*COL_SIZE)/2);
    curLen = 0;
    state = S_SHOW_SPACE;
    // fall through
  case S_SHOW_SPACE:	// display inter-character spacing (blank column)
    PRINT("\nS_ICSPACE: ", curLen);
    PRINT("/", showLen);
    curLen++;
    if (curLen == showLen)
      state = S_NEXT_CHAR;
    break;
  default:
    state = S_IDLE;
  }
  return(colData);
}
void scrollText(void)
{
  static uint32_t	prevTime = 0;
  // Is it time to scroll the text?
  if (millis() - prevTime >= SCROLL_DELAY)
  {
    mx.transform(MD_MAX72XX::TSL);	// scroll along - the callback will load all the data
    prevTime = millis();			// starting point for next time
  }
}
void setup()
{
#if DEBUG
  Serial.begin(115200);
  PRINTS("\n[MD_MAX72XX WiFi Message Display]\nType a message for the scrolling display from your internet browser");
#endif
#if LED_HEARTBEAT
  pinMode(HB_LED, OUTPUT);
  digitalWrite(HB_LED, LOW);
#endif
  // Display initialisation
  mx.begin();
  mx.setShiftDataInCallback(scrollDataSource);
  mx.setShiftDataOutCallback(scrollDataSink);
  curMessage[0] = newMessage[0] = '\0';
  // Connect to and initialise WiFi network
  PRINT("\nConnecting to ", ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED)
  {
    PRINT("\n", err2Str(WiFi.status()));
    delay(500);
  }
  PRINTS("\nWiFi connected");
  // Start the server
  server.begin();
  PRINTS("\nServer started");
  // Set up first message as the IP address
  sprintf(curMessage, "%03d:%03d:%03d:%03d", WiFi.localIP()[0], WiFi.localIP()[1], WiFi.localIP()[2], WiFi.localIP()[3]);
  PRINT("\nAssigned IP ", curMessage);
}
void loop()
{
#if LED_HEARTBEAT
  static uint32_t timeLast = 0;
  if (millis() - timeLast >= HB_LED_TIME)
  {
    digitalWrite(HB_LED, digitalRead(HB_LED) == LOW ? HIGH : LOW);
    timeLast = millis();
  }
#endif
  handleWiFi();
  scrollText();
}

Downloads:

  1. Arduino IDE
  2. ESP8266 Arduino Library
  3. MajicDesigns MD_MAX7219 Library
  4. Code.ino

Video:

How to solve mirror image and orientation problems of matrix display if you are using old MD_MAX72xx library.

]]> https://blog.etechpath.com/how-to-control-max7219-led-matrix-with-esp8266-wifi-module/feed/ 34 Bluetooth Controlled 8×8 LED MAX7219 Matrix using Android Phone. https://blog.etechpath.com/bluetooth-controlled-8x8-led-max7219-matrix-using-android-phone/ https://blog.etechpath.com/bluetooth-controlled-8x8-led-max7219-matrix-using-android-phone/#comments Thu, 12 Oct 2017 00:51:25 +0000 https://blog.etechpath.com/?p=416 About:

This project is about moving LED matrix display. In this project we will use MAX7219 8×8 LED module for display, Arduino UNO for brain and Bluetooth serial  module for communication. You will need an Android phone for controlling this display.




Things you will need: 

  1. Arduino UNO.
  2. MAX7219 LED modules – 3Nos.   (You can add many of these for increasing length of display)
  3. HC-05 Serial Bluetooth Module.      (You can use any other similar serial Bluetooth module instead )
  4. Android Phone.

 

Circuit Diagram:

Circuit Diagram

wiring diagram

 

Code :

    /*
          8x8 LED Matrix MAX7219 Scrolling Text
              Android Control via Bluetooth
    */
    #include <MaxMatrix.h>
    #include <SoftwareSerial.h>
    #include <avr/pgmspace.h>
    PROGMEM const unsigned char CH[] = {
      3, 8, B00000000, B00000000, B00000000, B00000000, B00000000, // space
      1, 8, B01011111, B00000000, B00000000, B00000000, B00000000, // !
      3, 8, B00000011, B00000000, B00000011, B00000000, B00000000, // "
      5, 8, B00010100, B00111110, B00010100, B00111110, B00010100, // #
      4, 8, B00100100, B01101010, B00101011, B00010010, B00000000, // $
      5, 8, B01100011, B00010011, B00001000, B01100100, B01100011, // %
      5, 8, B00110110, B01001001, B01010110, B00100000, B01010000, // &
      1, 8, B00000011, B00000000, B00000000, B00000000, B00000000, // '
      3, 8, B00011100, B00100010, B01000001, B00000000, B00000000, // (
      3, 8, B01000001, B00100010, B00011100, B00000000, B00000000, // )
      5, 8, B00101000, B00011000, B00001110, B00011000, B00101000, // *
      5, 8, B00001000, B00001000, B00111110, B00001000, B00001000, // +
      2, 8, B10110000, B01110000, B00000000, B00000000, B00000000, // ,
      4, 8, B00001000, B00001000, B00001000, B00001000, B00000000, // -
      2, 8, B01100000, B01100000, B00000000, B00000000, B00000000, // .
      4, 8, B01100000, B00011000, B00000110, B00000001, B00000000, // /
      4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // 0
      3, 8, B01000010, B01111111, B01000000, B00000000, B00000000, // 1
      4, 8, B01100010, B01010001, B01001001, B01000110, B00000000, // 2
      4, 8, B00100010, B01000001, B01001001, B00110110, B00000000, // 3
      4, 8, B00011000, B00010100, B00010010, B01111111, B00000000, // 4
      4, 8, B00100111, B01000101, B01000101, B00111001, B00000000, // 5
      4, 8, B00111110, B01001001, B01001001, B00110000, B00000000, // 6
      4, 8, B01100001, B00010001, B00001001, B00000111, B00000000, // 7
      4, 8, B00110110, B01001001, B01001001, B00110110, B00000000, // 8
      4, 8, B00000110, B01001001, B01001001, B00111110, B00000000, // 9
      2, 8, B01010000, B00000000, B00000000, B00000000, B00000000, // :
      2, 8, B10000000, B01010000, B00000000, B00000000, B00000000, // ;
      3, 8, B00010000, B00101000, B01000100, B00000000, B00000000, // <
      3, 8, B00010100, B00010100, B00010100, B00000000, B00000000, // =
      3, 8, B01000100, B00101000, B00010000, B00000000, B00000000, // >
      4, 8, B00000010, B01011001, B00001001, B00000110, B00000000, // ?
      5, 8, B00111110, B01001001, B01010101, B01011101, B00001110, // @
      4, 8, B01111110, B00010001, B00010001, B01111110, B00000000, // A
      4, 8, B01111111, B01001001, B01001001, B00110110, B00000000, // B
      4, 8, B00111110, B01000001, B01000001, B00100010, B00000000, // C
      4, 8, B01111111, B01000001, B01000001, B00111110, B00000000, // D
      4, 8, B01111111, B01001001, B01001001, B01000001, B00000000, // E
      4, 8, B01111111, B00001001, B00001001, B00000001, B00000000, // F
      4, 8, B00111110, B01000001, B01001001, B01111010, B00000000, // G
      4, 8, B01111111, B00001000, B00001000, B01111111, B00000000, // H
      3, 8, B01000001, B01111111, B01000001, B00000000, B00000000, // I
      4, 8, B00110000, B01000000, B01000001, B00111111, B00000000, // J
      4, 8, B01111111, B00001000, B00010100, B01100011, B00000000, // K
      4, 8, B01111111, B01000000, B01000000, B01000000, B00000000, // L
      5, 8, B01111111, B00000010, B00001100, B00000010, B01111111, // M
      5, 8, B01111111, B00000100, B00001000, B00010000, B01111111, // N
      4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // O
      4, 8, B01111111, B00001001, B00001001, B00000110, B00000000, // P
      4, 8, B00111110, B01000001, B01000001, B10111110, B00000000, // Q
      4, 8, B01111111, B00001001, B00001001, B01110110, B00000000, // R
      4, 8, B01000110, B01001001, B01001001, B00110010, B00000000, // S
      5, 8, B00000001, B00000001, B01111111, B00000001, B00000001, // T
      4, 8, B00111111, B01000000, B01000000, B00111111, B00000000, // U
      5, 8, B00001111, B00110000, B01000000, B00110000, B00001111, // V
      5, 8, B00111111, B01000000, B00111000, B01000000, B00111111, // W
      5, 8, B01100011, B00010100, B00001000, B00010100, B01100011, // X
      5, 8, B00000111, B00001000, B01110000, B00001000, B00000111, // Y
      4, 8, B01100001, B01010001, B01001001, B01000111, B00000000, // Z
      2, 8, B01111111, B01000001, B00000000, B00000000, B00000000, // [
      4, 8, B00000001, B00000110, B00011000, B01100000, B00000000, // \ backslash
      2, 8, B01000001, B01111111, B00000000, B00000000, B00000000, // ]
      3, 8, B00000010, B00000001, B00000010, B00000000, B00000000, // hat
      4, 8, B01000000, B01000000, B01000000, B01000000, B00000000, // _
      2, 8, B00000001, B00000010, B00000000, B00000000, B00000000, // `
      4, 8, B00100000, B01010100, B01010100, B01111000, B00000000, // a
      4, 8, B01111111, B01000100, B01000100, B00111000, B00000000, // b
      4, 8, B00111000, B01000100, B01000100, B00101000, B00000000, // c
      4, 8, B00111000, B01000100, B01000100, B01111111, B00000000, // d
      4, 8, B00111000, B01010100, B01010100, B00011000, B00000000, // e
      3, 8, B00000100, B01111110, B00000101, B00000000, B00000000, // f
      4, 8, B10011000, B10100100, B10100100, B01111000, B00000000, // g
      4, 8, B01111111, B00000100, B00000100, B01111000, B00000000, // h
      3, 8, B01000100, B01111101, B01000000, B00000000, B00000000, // i
      4, 8, B01000000, B10000000, B10000100, B01111101, B00000000, // j
      4, 8, B01111111, B00010000, B00101000, B01000100, B00000000, // k
      3, 8, B01000001, B01111111, B01000000, B00000000, B00000000, // l
      5, 8, B01111100, B00000100, B01111100, B00000100, B01111000, // m
      4, 8, B01111100, B00000100, B00000100, B01111000, B00000000, // n
      4, 8, B00111000, B01000100, B01000100, B00111000, B00000000, // o
      4, 8, B11111100, B00100100, B00100100, B00011000, B00000000, // p
      4, 8, B00011000, B00100100, B00100100, B11111100, B00000000, // q
      4, 8, B01111100, B00001000, B00000100, B00000100, B00000000, // r
      4, 8, B01001000, B01010100, B01010100, B00100100, B00000000, // s
      3, 8, B00000100, B00111111, B01000100, B00000000, B00000000, // t
      4, 8, B00111100, B01000000, B01000000, B01111100, B00000000, // u
      5, 8, B00011100, B00100000, B01000000, B00100000, B00011100, // v
      5, 8, B00111100, B01000000, B00111100, B01000000, B00111100, // w
      5, 8, B01000100, B00101000, B00010000, B00101000, B01000100, // x
      4, 8, B10011100, B10100000, B10100000, B01111100, B00000000, // y
      3, 8, B01100100, B01010100, B01001100, B00000000, B00000000, // z
      3, 8, B00001000, B00110110, B01000001, B00000000, B00000000, // {
      1, 8, B01111111, B00000000, B00000000, B00000000, B00000000, // |
      3, 8, B01000001, B00110110, B00001000, B00000000, B00000000, // }
      4, 8, B00001000, B00000100, B00001000, B00000100, B00000000, // ~
    };
    int dIn = 7;   // DIN pin of MAX7219 module
    int clk = 6;   // CLK pin of MAX7219 module
    int cs = 5;    // CS pin of MAX7219 module
    int maxInUse = 2;    // Number of MAX7219's connected
    MaxMatrix m(dIn, cs, clk, maxInUse);
    SoftwareSerial Bluetooth(8, 7); // Bluetooth
    byte buffer[10];
    char incomebyte;
    int scrollSpeed = 100;
    char text[100] = "www.etechpath.com  "; // Initial text message
    int brightness = 15;
    int count = 0;
    char indicator;
    void setup() {
      m.init(); // MAX7219 initialization
      m.setIntensity(brightness); // initial led matrix intensity, 0-15
      Bluetooth.begin(38400); // Default communication rate of the Bluetooth module
    }
    void loop() {
      // Printing the text
      printStringWithShift(text, scrollSpeed);
      
      if (Bluetooth.available()) {   // Checks whether data is comming from the serial port
        indicator = Bluetooth.read();   // Starts reading the serial port, the first byte from the incoming data
        // If we have pressed the "Send" button from the Android App, clear the previous text
        if (indicator == '1') {
          for (int i = 0; i < 100; i++) {
            text[i] = 0;
            m.clear();
          }
          // Read the whole data/string comming from the phone and put it into text[] array.
          while (Bluetooth.available()) {
            incomebyte = Bluetooth.read();
            text[count] = incomebyte;
            count++;
          }
          count = 0;
        }
        // Adjusting the Scrolling Speed
        else if (indicator == '2') {
          String sS = Bluetooth.readString();
          scrollSpeed = 150 - sS.toInt(); // Milliseconds, subtraction because lower value means higher scrolling speed
        }
        // Adjusting the brightness
        else if (indicator == '3') {
          String sB = Bluetooth.readString();
          brightness = sB.toInt();
          m.setIntensity(brightness);
        }
      }
    }
    void printCharWithShift(char c, int shift_speed) {
      if (c < 32) return;
      c -= 32;
      memcpy_P(buffer, CH + 7 * c, 7);
      m.writeSprite(32, 0, buffer);
      m.setColumn(32 + buffer[0], 0);
      for (int i = 0; i < buffer[0] + 1; i++)
      {
        delay(shift_speed);
        m.shiftLeft(false, false);
      }
    }
    void printStringWithShift(char* s, int shift_speed) {
      while (*s != 0) {
        printCharWithShift(*s, shift_speed);
        s++;
      }
    }
    void printString(char* s)
    {
      int col = 0;
      while (*s != 0)
      {
        if (*s < 32) continue;
        char c = *s - 32;
        memcpy_P(buffer, CH + 7 * c, 7);
        m.writeSprite(col, 0, buffer);
        m.setColumn(col + buffer[0], 0);
        col += buffer[0] + 1;
        s++;
      }
    }

 

 

Steps :

  1. Connect MAX7219 LED modules with each other as shown in above wiring diagram.
  2. Connect led modules data pins to arduino data pins and connect source power as shown in circuit diagram.
  3. Now connect HC-05 serial module to RX TX pins of Arduino. Arduino RX to HC-05 TX and arduino TX to HC-05 RX.
  4. Download code into arduino using Arduino IDE.
  5. Download android application from download section and install it in your phone .
  6. Now you can connect your phone with this display using provided application to control matrix display.



Downloads :

  1. Android appliation
  2. MAX7219 Datasheet
  3. MaxMatrix.h


Check this WiFi controlled MAX7219 LED Matrix using ESP-12 NodeMCU module

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