4 digit 7 segment display

Using Arduino Project Guidance
1

Hi I have a 4 digit 7 segment display with the setup: Arduino 4 Digit 7 Segment Display Tutorial
Now I'm using the code:

int i=0;
 
void setup()
{
 DDRD=0xff; // all pins 0-7 OUTPUTs
 DDRB=0xff; // all pins 8-13 OUTPUTs even though we only use pins 8-12
 PORTD=0x00; // make pins 0-7 LOWs
 PORTB=0x00; // make pins 8-13 LOWs
}
 
void loop()
{
  
  while(1){
  
  turnOnSquare(1);
  displayDigit(8);
  delay(2);
  turnOnSquare(2);
  displayDigit(8);
  delay(2);
  turnOnSquare(3);
  displayDigit(8);
  delay(2);
  turnOnSquare(4);
  displayDigit(8);
  delay(2);
  }
 
}
// paste the two functions after this line.
void displayDigit(int num)
{
   switch(num)
   {
     case 0:
      PORTD=B00000011; // pins 2-7 on
      digitalWrite(8,HIGH); // turn off pin 8
     break;
     case 1:
      PORTD=B11100111; // only pins 2 and 3 are on
      digitalWrite(8,HIGH); // turn off pin 8
     break;
     case 2:
      PORTD=B10010011; // only pins 2,3,5 and 6 on
      digitalWrite(8,LOW); // segment g on
     break;
     case 3:
      PORTD=B11000011; // only pins 2,3,4 and 5 on
      digitalWrite(8,LOW); // segment g on
     break;
     case 4:
      PORTD=B01100111; // only pins 3,4 and 7 on
      digitalWrite(8,LOW); // segment g on
     break;
     case 5:
      PORTD=B01001011; //B10110100; // only pins 2,4,5 and 7 on
      digitalWrite(8,LOW); // segment g on
     break;
     case 6:
      PORTD=B00001011; //B11110100; // only pins 2,4,5,6 and 7 on
      digitalWrite(8,LOW); // segment g on
     break;
     case 7:
      PORTD=B11100011; // only pins 2,3 and 4 on
      digitalWrite(8,HIGH); // segment g off
     break;
     case 8:
      PORTD=B00000011; // pins 2-7 on
      digitalWrite(8,LOW); // turn on pin 8
     break;
     case 9:
      PORTD=B01000011; // only pins 2,3, 4 and 5 on
      digitalWrite(8,LOW); // segment g on
     break;
   }
}
   void turnOnSquare(int num)
{
int d1=9,d2=10,d3=11,d4=12;
 switch(num)
 {
   case 1:
    digitalWrite(d2,LOW);
    digitalWrite(d3,LOW);
    digitalWrite(d4,LOW);
    digitalWrite(d1,HIGH);
   break;
   case 2:
    digitalWrite(d1,LOW);
    digitalWrite(d3,LOW);
    digitalWrite(d4,LOW);
    digitalWrite(d2,HIGH);
   break;
   case 3:
    digitalWrite(d1,LOW);
    digitalWrite(d2,LOW);
    digitalWrite(d4,LOW);
    digitalWrite(d3,HIGH);
   break;
   case 4:
    digitalWrite(d1,LOW);
    digitalWrite(d2,LOW);
    digitalWrite(d3,LOW);
    digitalWrite(d4,HIGH);
   break;
   default:
   // this should never occur, but do what you want here
   break;
 }
 
}

So when I turn it on it displays 88:88 like I want it to but lets say I change the code so it'll display 12:34. It displays the top part of the one but not the top part of the two, the three is fine and the bottom leg of the four is gone. It works when I have all 8's so a segment isn't blown but it still act funny.

Please help

2

Is the 7 segment display pinouts the same as the tutorial one? If it's the same then the problem is you probably have the segment wiring wrong. Try turning on one segment at a time to confirm it's correct.

3

You might also have a short between two segments - this can cause odd pattern-sensitive errors. Try writing test code that lights one segment at a time for each digit in turn - that will show any wiring issues.

4

this happened on a display of mine after i put a lower then needed resistor on one of the pins, and it messed up the internals of the display (no externally visible damage though).

Another thing is you should maybe check the high low reqs for the display. you might just be telling it to turn on and off the wrong pins