four_seven_led.ino

// assigning arduino digital pins for the various led display pins
int pinA = 3;
int pinB = 7;
int pinC = 12;
int pinD = 10;
int pinE = 9;
int pinF = 4;
int pinG = 13;
int pinDP = 11; // the decimal point pin
int D1 = 2;
int D2 = 5;
int D3 = 6;
int D4 = 8;
int t = 250; // time delay

void setup() 
{                
  // initialise the digital pins as outputs.
  pinMode(pinA, OUTPUT);     
  pinMode(pinB, OUTPUT);     
  pinMode(pinC, OUTPUT);     
  pinMode(pinD, OUTPUT);     
  pinMode(pinE, OUTPUT);     
  pinMode(pinF, OUTPUT);     
  pinMode(pinG, OUTPUT);   
  pinMode(pinDP, OUTPUT);  
  pinMode(D1, OUTPUT);  
  pinMode(D2, OUTPUT);  
  pinMode(D3, OUTPUT);  
  pinMode(D4, OUTPUT);  
}

void loop() 
{ 
  write_D1(); //function call to turn on D1 to write characters for the first digit
  print_3(); // function call to display 3
  print_decimal(); // function call to display the decimal point
  delay(1);

  write_D2(); //function call to turn on D2 to write characters for the second digit
  print_1(); // function call to display 1
  delay(1);

  write_D3(); //function call to turn on D3 to write characters for the third digit
  print_4(); // function call to display 4
  delay(1);

  write_D4(); //function call to turn on D4 to write characters for the fourth digit
  print_2(); // function call to display 2
  delay(1);
}



/* THE FUNCTIONS */



// the functions for selecting the common pin to turn on
void write_D1()
{
  digitalWrite(D1, LOW);
  digitalWrite(D2, HIGH);
  digitalWrite(D3, HIGH);
  digitalWrite(D4, HIGH); 
}

void write_D2()
{
  digitalWrite(D1, HIGH);
  digitalWrite(D2, LOW);
  digitalWrite(D3, HIGH);
  digitalWrite(D4, HIGH); 
}

void write_D3()
{
  digitalWrite(D1, HIGH);
  digitalWrite(D2, HIGH);
  digitalWrite(D3, LOW);
  digitalWrite(D4, HIGH); 
}

void write_D4()
{
  digitalWrite(D1, HIGH);
  digitalWrite(D2, HIGH);
  digitalWrite(D3, HIGH);
  digitalWrite(D4, LOW); 
}

// the functions for writing characters to the display
void print_0() // writing 0
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW); // the decimal point is always off by default
}

void print_1() // writing 1
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_2() // writing 2
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_3() // writing 3
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_4() // writing 4
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_5() // writing 5
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_6() // writing 6
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_7() // writing 7
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_8() // writing 8
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_9() // writing 9
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_A() // writing A
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_b() // writing b
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_C() // writing C
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_d() // writing d
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_E() // writing E
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_F() // writing F
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_H() // writing H
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_h() // writing h
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_J() // writing J
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_L() // writing L
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_n() // writing n
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);   
}

void print_O() // writing O
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_o() // writing o
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_P() // writing P
{
  digitalWrite(pinA, HIGH);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_r() // writing r
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_t() // writing t
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_u() // writing u
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, HIGH);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_y() // writing y
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, HIGH);   
  digitalWrite(pinC, HIGH);   
  digitalWrite(pinD, HIGH);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, HIGH);   
  digitalWrite(pinG, HIGH);
  digitalWrite(pinDP, LOW);
}

void print_decimal() // writing the decimal point
{
  digitalWrite(pinDP, HIGH);
}

void print_OFF() // turning all 7 segments plus the decimal point off
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}

void print_off() // turning all 7 segments plus the decimal point off
{
  digitalWrite(pinA, LOW);   
  digitalWrite(pinB, LOW);   
  digitalWrite(pinC, LOW);   
  digitalWrite(pinD, LOW);   
  digitalWrite(pinE, LOW);   
  digitalWrite(pinF, LOW);   
  digitalWrite(pinG, LOW);
  digitalWrite(pinDP, LOW);
}