7 segment LED display
by Jose Ojeda

Shows how to drive a 7 segment LED display. The display shows the numbers from 0 to 9 over and over. Those displays can be common anode (the segments will be ON by turning the pins LOW) or common cathode (the segments will be ON by turning the pins HIGH).

Created 1 May 2007
 

    
// 7 segment LED display 
// by Jose Ojeda 

 
int number = 0;      // variable the keeps number number in the display 
 
void turn_all_off() {  // function to turn off all the lights 
  for(int i=0; i<8; i++) { 
    digitalWrite(i, LOW); 
  } 
} 
 
void setup() { 
  for(int i=0; i<8; i++) {  // initializes pins 0 to 7 as outputs 
    pinMode(i, OUTPUT); 
  } 
} 
 
void loop() { 
  turn_all_off(); // turns the display off 
  if(number==0) { 
    digitalWrite(5, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(0, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==1) { 
    digitalWrite(2, HIGH); 
    digitalWrite(7, HIGH); 
  } 
  if(number==2) { 
    digitalWrite(7, HIGH); 
    digitalWrite(4, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(0, HIGH); 
    digitalWrite(1, HIGH); 
  } 
  if(number==3) { 
    digitalWrite(4, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==4) { 
    digitalWrite(5, HIGH); 
    digitalWrite(4, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==5) { 
    digitalWrite(4, HIGH); 
    digitalWrite(5, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==6) { 
    digitalWrite(4, HIGH); 
    digitalWrite(5, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(0, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==7) { 
    digitalWrite(6, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==8) { 
    digitalWrite(4, HIGH); 
    digitalWrite(5, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(0, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  if(number==9) { 
    digitalWrite(4, HIGH); 
    digitalWrite(5, HIGH); 
    digitalWrite(6, HIGH); 
    digitalWrite(7, HIGH); 
    digitalWrite(1, HIGH); 
    digitalWrite(2, HIGH); 
  } 
  delay(1000); // waits for 1000 milli seconds 
  number = number + 1; // increments the variable to show 
  if(number > 9) {  // check for the range, if greater then 9 goes back to 0s  
    number = 0; 
  } 
}