While writing my previous post on 7 segment LED, I wondered, if could write code for displaying alphabetical character on 7 segment LED. So in this post, I want to share with you my arduino codes using which you can see how alphabetic characters can be displayed on a 7 segment LED. This program is quite different from the program shared in the previous post because unlike the previous program on 7 segment LED wherein all the numbers were automatically displayed one by one, in this post you can see your desired character only after you press that key in the Serial Monitor. Alternatively, you can also use 'Hyperterminal' or 'Docklight' for sending data through serial port.

The demo video of this experiment and the complete code is given below. You can also download the full code in a single file from this link.

Please note that the 7 segment LED is connected in common anode mode, that means all 7 anodes of leds are connected together and should be connected to +5V and a particular LED will turn on when ‘Ground’ is applied to its terminal, which in this case is done using microcontroller. (For more details on the theoretical part refer previous post on 7 segment LED).

Demo Video:




Arduino Code:

int a=2;
int b=3;
int c=4;
int d=5;
int e=6;
int f=7;
int g=8;
int p=9;
void setup()
{
  pinMode(a,OUTPUT);
  pinMode(b,OUTPUT);
  pinMode(c,OUTPUT);
  pinMode(d,OUTPUT);
  pinMode(e,OUTPUT);
  pinMode(f,OUTPUT);
  pinMode(g,OUTPUT);
  pinMode(p,OUTPUT);
  Serial.begin(9600);
}
void loop()
{
  digitalWrite(p,HIGH);
  while(Serial.available()==0);
  
  char letter=Serial.read();
  Serial.println(letter);

  switch(letter)
  {
    case 'A':
      showa();
      break;
    case 'B':
      showb();
      break;
    case 'C':
      showc();
      break;
     case 'D':
       showd();
       break;
     case 'E':
       showe();
       break;
      case 'F':
        showf();
        break;
      case 'G':
        showg();
        break;
      case 'H':
        showh();
        break;
      case 'I':
        showi();
        break;
      case 'J':
        showj();
        break;
      case 'K':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'L':
        showl();
        break;
      case 'M':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'N':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'O':
        showo();
        break;
      case 'P':
        showp();
        break;
      case 'Q':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'R':
        showr();
        break;
      case 'S':
        shows();
        break;
      case 'T':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'U':
        showu();
        break;
      case 'V':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'W':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'X':
        point_blink(); //indicating it is not possible to display the specified character
        break;
      case 'Y':
        showy();
        break;
      case 'Z':
        showz();
        break;
      default:
        Serial.println("unknown character\nTry typing alphabets in CAPITAL");
  }
  
}
void showa()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,HIGH);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showb()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showc()
{
  digitalWrite(a,LOW);
  digitalWrite(b,HIGH);
  digitalWrite(c,HIGH);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);
}
void showd()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);
}
void showe()
{
  digitalWrite(a,LOW);
  digitalWrite(b,HIGH);
  digitalWrite(c,HIGH);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showf()
{
  digitalWrite(a,LOW);
  digitalWrite(b,HIGH);//high
  digitalWrite(c,HIGH);//high
  digitalWrite(d,HIGH);//high
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showg()
{
  digitalWrite(a,LOW);
  digitalWrite(b,HIGH);//high
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);//high
}
void showh()
{
  digitalWrite(a,HIGH);//high
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,HIGH);//high
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showi()
{
  digitalWrite(a,HIGH);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,HIGH);
  digitalWrite(e,HIGH);
  digitalWrite(f,HIGH);
  digitalWrite(g,HIGH);
}
void showj()
{
  digitalWrite(a,HIGH);//HIGH
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,HIGH);//high
  digitalWrite(g,HIGH);//high
}
void showl()
{
  digitalWrite(a,HIGH);
  digitalWrite(b,HIGH);
  digitalWrite(c,HIGH);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);
}
void showo()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);
}
void showp()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,HIGH);//HIGH
  digitalWrite(d,HIGH);//HIGH
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showr()
{
  //looks same as A
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,HIGH);//high
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void shows()
{
  digitalWrite(a,LOW);
  digitalWrite(b,HIGH);//high
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,HIGH);//high
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showu()
{
  digitalWrite(a,HIGH);//high
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,LOW);
  digitalWrite(g,HIGH);
}
void showy()
{
  digitalWrite(a,HIGH);//high
  digitalWrite(b,LOW);
  digitalWrite(c,LOW);
  digitalWrite(d,HIGH);//high
  digitalWrite(e,HIGH);//high
  digitalWrite(f,LOW);
  digitalWrite(g,LOW);
}
void showz()
{
  digitalWrite(a,LOW);
  digitalWrite(b,LOW);
  digitalWrite(c,HIGH);//high
  digitalWrite(d,LOW);
  digitalWrite(e,LOW);
  digitalWrite(f,HIGH);//high
  digitalWrite(g,LOW);
}
void point_blink()
{
  Serial.println("Not Possible to display this character");
  digitalWrite(a,HIGH);
  digitalWrite(b,HIGH);
  digitalWrite(c,HIGH);//high
  digitalWrite(d,HIGH);
  digitalWrite(e,HIGH);
  digitalWrite(f,HIGH);//high
  digitalWrite(g,HIGH);
  for(int i=0;i<20;i++)
  {
    digitalWrite(p,LOW);
    delay(100);
    digitalWrite(p,HIGH);
    delay(100);
  }
}