Using 74hc595 12 unit of 4 digit 7segment

Other Hardware LEDs and Multiplexing
1

My project required to display on 12 unit of 4 digit 7segment. Im planning to use 74hc595 as being use in this link Arduino and two 595 with a 4 digit 7 segment LED display - Anything Arduino ep 22 - YouTube.

There is no problem to control the first 1 unit. But the problem is when i want to use 12 unit of 4 digit at the same time.

2

Hi, and welcome to the forum.
To get proper help, you need to post your code and a wiring diagram or picture(s).
Read the forum rules about posting with code tags.

This project could be easier/cheaper if you use 8-digit modules with integrated MAX 7219 driver chip.
Nothing else needed, and they can be daisy-chained to as many as you like.
Search for "8-digit MAX7219" on ebay.
Leo.

3

Wawa:
This project could be easier/cheaper if you use 8-digit modules with integrated MAX 7219 driver chip.
Nothing else needed, and they can be daisy-chained to as many as you like.
Search for "8-digit MAX7219" on ebay.
Leo.

++
I swapped over to using these a year ago; brilliant little units. Also controlled by the 7219 are the 8x8 led matrix modules which I have used to make a "ticker tape" type display.

4

Here is my code

int latchPin = 2; //pin 12 on the 595
int dataPin = 3; //pin 14 on the 595
int clockPin = 4; //pin 11 on the 595

int numHex[] = {63, 6, 91, 79, 102, 109, 125, 7, 127, 103};
int daerah[4][4] ={ // {latchPin, dataPin, clockPin, input}
  {2, 3, 4, 2342}, // johor
  {5, 6, 7, 4321},
  {8, 9, 10, 7834},
  {11, 12, 13, 4321},
  {14, 15, 16, 7834},
  {17, 18, 19, 4321},
  {20, 21, 22, 7834},
  {23, 24, 25, 4321},
  {26, 27, 28, 7834},
  {29, 30, 31, 7834},
  {32, 33, 34, 394}
};
void setup() {
  Serial.begin(9600);
  for (int i = 1; i < 14; i++){
    pinMode(i, OUTPUT);
  }
}

void loop() {
  for( int i = 0; i < 4; i++){
    display(daerah[i][0],daerah[i][1],daerah[i][2],daerah[i][3]);
  }
}

void display(int latchPin, int dataPin, int clockPin, int num){
  int num1=num/1000;
  int num2=(num/100)-(num1*10);
  int num3=(num/10)-(num1*100)-(num2*10);
  int num4=num-(num1*1000)-(num2*100)-(num3*10);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST,63);
  shiftOut(dataPin, clockPin, MSBFIRST,numHex[num1]);
  digitalWrite(latchPin, HIGH);
  delay(1);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + 63 << 1);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + numHex[num2]);
  digitalWrite(latchPin, HIGH);
  delay(1);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + 63 >> 5);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + numHex[num3]);
  digitalWrite(latchPin, HIGH);
  delay(1);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + 63 >> 4);
  shiftOut(dataPin, clockPin, MSBFIRST,128 + numHex[num4]);
  digitalWrite(latchPin, HIGH);
  delay(1);
}

The code is fine. its working.

But the problem is when i want to make the 12 unit (4 digit 7 segment).
The light start to dimm and some number doesn't appear. So i add 4 transistor(2n2222) for
each digit. the brightness is getting better. but the problem is its only display '2222' instead of '2342'.

5

One obvious thing wrong (but I suspect not what is causing your problem) is that you initialize
int daerah[4][4] with124 odd values instead of 44 values.

More of a problem is that you set pinMode() to OUTPUT on pins 1 to 14 inclusive yet you use pins 2,3 4 etc to 34 inclusive.

I really don't understand your code. In order to help understand your code I would like to see a wiring diagram; one of the blocks of seven segments would probably be enough.

6

If you would like to use MAX7219 try this site for wiring. You need to scroll down about half way.
.Gammon Forum : Electronics : Microprocessors : Interfacing LED displays with the MAX7219 driver