P10 DMD Display

P10 DMD Display With Arduino and RTC DS3231

Introduction:P10 displays are an array of dot matrix LEDs. P10 led is generally known as a Dot Matrix Display or DMD display. It is based on shift registers, generally 74595shift registers are used. They can be cascaded with more number of such similar boards. Available in various sizes and LED colors, we'll be using here 32*16 type.We can display scrollable text, stylised text with various font sizes.They are very much popular in commercial display boards like shops,stations,airports,etc. Best thing about them is that they can be interfaced with any standard microcontroller without the need of any special communication protocols.we will be using arduino to use it.We'll be using it to generate a text along with the current time and date.

Step 1: Parts Required

1. P10 display with 16 Pin FRC connector ribbon cable
2. arduino (uno/mega/nano/pro mini)
3. ds3231
4. male and female headers
5. veroboard and soldering kits
6. jumpers (only required for initial testing)
7. 5v 1A power supply

Step 2: Understanding Circuit and Procedure

On the back side of the P10 board, there are two sets of ports.The data input and output port for cascading. The DS3231 is the real time clock (RTC). It is used to show date and time.
The circuit diagram is attached here. Don't use the 5v 1a external supply now. The arduino power can lit your display up (dim light) sufficiently enough for testing.
DS3231 uses I2C communication protocol. Attach the CR2302 battery holder in it's place and connect its i2c pins with arduino i2c. If you're new to this module check out this link below: https://howtomechatronics.com/tutorials/arduino/arduino-ds3231-real-time-clock-tutorial/
Now follow the circuit diagram and attach jumpers from the P10 board to arduino. This connections to be made obviously at the input port of the P10.
The 16 Pin FRC connector-1 ribbon cable is used for both input and output port which can be used later, after you've made the finalized veroboard circuit.

Step 3: Uploading Code and Testing

Download the codes attached below. It is pretty much self explanatory. Library links given here.
https://github.com/freetronics/DMD
https://www.arduinolibraries.info/libraries/dmd2

I will suggest you to install both, since both contains many unique features.
You may upload any of the codes which are written below. Also you may wish to use any inbuild example sketches.
Rewrite it to show your own text and desired font settings. Upload it.
You should see your desired output on the screen

First 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
DS3231  rtc(SDA, SCL);
//Fire up the DMD library as dmd
#define DISPLAYS_ACROSS 1
#define DISPLAYS_DOWN 1
DMD dmd(DISPLAYS_ACROSS, DISPLAYS_DOWN);

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

void setup(void)
{
   rtc.begin();
   //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 (5ms) 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)

}

void loop(void)
{
  String x=rtc.getDOWStr();
  x=x.substring(0,3);
  char a[4];
  x.toCharArray(a,4);
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.drawString(8, 3, a,4, GRAPHICS_NORMAL); // Display TEXT SFE
  delay(2000);

  dmd.clearScreen( true );
  x=rtc.getDateStr(); // Display TEXT SF
  char b[12];
  dmd.selectFont(Arial_Black_16);
  x.toCharArray(b,12);
  dmd.drawMarquee(b,12,(32*DISPLAYS_ACROSS)-1,0);
   long start=millis();
   long timer=start;
   boolean ret=false;
   while(!ret){
     if ((timer+40)<millis()) {
       ret=dmd.stepMarquee(-1,0);
       timer=millis();
     }
   }


  dmd.clearScreen( true );
  x=rtc.getTimeStr(); // Display TEXT SF
  x=x.substring(0,6);
  char c[6];
  x.toCharArray(c,6);
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.drawString(1, 5, c,6, GRAPHICS_NORMAL); // Display TEXT SFE
  delay(3000);
 

   
   // 10 x 14 font clock, including demo of OR and NOR modes for pixels so that the flashing colon can be overlayed
   dmd.clearScreen( true );
   dmd.selectFont(Arial_Black_16);
   dmd.drawMarquee("TECHNO INDIA UNIVERSITY : Celebration Of National Science Day and World Engineering Day For Sustainable Development ",115,(32*DISPLAYS_ACROSS)-1,0);
   start=millis();
   timer=start;
   ret=false;
   while(!ret){
     if ((timer+40)<millis()) {
       ret=dmd.stepMarquee(-1,0);
       timer=millis();
     }
   }
 
 }

Second Code


#include 
#include
#include 
#include 
#include "SystemFont5x7.h"
#include 
SoftDMD dmd(1,1);
// Number of P10 panels used X, Y
// Set Box (dmd, x, y, Height, Width) 
 DS3231  rtc(SDA, SCL);
 
void setup() {
  // Setup Serial connection
  Serial.begin(9600); 
  // Initialize the rtc object
  rtc.begin();
}

void loop(){
  DMD_TextBox box(dmd, 1, 1, 32, 16); 
  dmd.setBrightness(125); // Set brightness 0 - 255 
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.begin();     // Start DMD 
  //box.print("ECE"); // Display TEXT SFE
  
  const char *MESSAGE = "TECHNO INDIA UNIVERSITY";
   const char *next = MESSAGE;
  while(*next) {
    Serial.print(*next);
    box.print(*next);
    delay(200);
    next++;
  }
   delay(1000);

  DMD_TextBox box8(dmd, 1, 1, 32, 16); 
  dmd.setBrightness(125); // Set brightness 0 - 255 
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.begin();     // Start DMD 
  //box.print("ECE"); // Display TEXT SFE
  
  const char *MESSAGE1 = "DEPT.";
   const char *next1 = MESSAGE1;
  while(*next1) {
    Serial.print(*next1);
    box8.print(*next1);
    delay(200);
    next1++;
  }
   delay(1000);
    
  DMD_TextBox box1(dmd, 6, 1, 32, 16); 
   // Send Day-of-Week
  Serial.print(rtc.getDOWStr());
  Serial.print(" "); 
  String x=rtc.getDOWStr();
   dmd.setBrightness(125); // Set brightness 0 - 255 
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.begin();     // Start DMD 
  box1.print(x.substring(0,3)); // Display TEXT SFE
  delay(2000);

   DMD_TextBox box2(dmd, 1, 1, 32, 16); 
  // Send date
  Serial.print(rtc.getDateStr());
  Serial.print(" -- ");
   dmd.setBrightness(125); // Set brightness 0 - 255 
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.begin();     // Start DMD 
  box2.print(rtc.getDateStr()); // Display TEXT SFE
  delay(3000);

   DMD_TextBox box3(dmd, 1, 1, 32, 16); 
  // Send time
  Serial.println(rtc.getTimeStr());
   x=rtc.getTimeStr();
   dmd.setBrightness(125); // Set brightness 0 - 255 
  dmd.selectFont(SystemFont5x7); // Font used
  dmd.begin();     // Start DMD 
  box3.print(x.substring(0,6)); // Display TEXT SFE
  delay(3000);
  }

Step 4: Finalizing

If everything is working fine then attach everything on veroboard and solder them. Use female headers to place arduino and ds3231, so that you can plug out reuse it in future for any other purpose.
Then use male headers to make the connector for the FRC ribbon cable of the p10 display (input port). Now test with continuity of multimeter if all connection are made properly. If ok now again power with usb to see if it shows the required text.If ok then remove usb and now attach the external 5v 1a power supply to it. It should now lit up brightly. So congrats you're now good to go with your display and place it in a distant place to see it.