/* Up/down-counter and seven segment display

Circuit Connections:
Seven segment common Cathode = > Gnd
PIN_3   =>  Resistor 220Ω => Segment f
PIN_4   =>  Resistor 220Ω => Segment g
PIN_5   =>  Resistor 220Ω => Segment d
PIN_6   =>  Resistor 220Ω => Segment e
PIN_8   =>  Resistor 220Ω => Segment a
PIN_9   =>  Resistor 220Ω => Segment b
PIN_10 =>  Resistor 220Ω => Segment c

PIN_0 => Serial_RX
PIN_1 => Serial_TX
*/

#define A_pin 8  //give the name “A_pin” to PIN_8
#define B_pin 9 //give the name “B_pin” to PIN_9
#define C_pin 10  //give the name “C_pin” to PIN_10
#define D_pin 5 //give the name “D_pin” to PIN_5
#define E_pin 6 //give the name “E_pin” to PIN_6
#define F_pin 3 //give the name “F_pin” to PIN_3
#define G_pin 4 //give the name “G_pin” to PIN_4

boolean count=true;     //true=up-counter, false=down-counter
String input; //variable to save data from serial
int i=0; // variable to hold the number for the seven segment display

//The setup() function initializes and sets the initial values
//It will only run once after each powerup or reset
void setup() {
  pinMode(A_pin, OUTPUT);  //Configure the PIN_8 to behave as output
  pinMode(B_pin, OUTPUT);  //Configure the PIN_9 to behave as output
  pinMode(C_pin, OUTPUT);  //Configure the PIN_10 to behave as output
  pinMode(D_pin, OUTPUT);  //Configure the PIN_5 to behave as output
  pinMode(E_pin, OUTPUT);  //Configure the PIN_6 to behave as output
  pinMode(F_pin, OUTPUT);  //Configure the PIN_3 to behave as output
  pinMode(G_pin, OUTPUT);  //Configure the PIN_4 to behave as output
  //opens serial port, sets data rate to 9600 bps
  Serial.begin(9600);
}


//This function loops consecutively
void loop() {
  //call the function “sevenSegment” and display the number “i”
  sevenSegment(i);
  delay(500);  //wait for 0.5s

  //check for serial data
  if (Serial.available() > 0){
    //read and save data
    input = Serial.readString();
    //check data’s value
    if(input == "up"){
      count=true; //up-counter
    }
    else if(input=="down"){
      count=false;  //down-counter
    }
   else{
     Serial.println("Wrong command");
    }
  }
  

//increase (or decrease) the number and check for overflow
  if (count == true){
    i++;
    if(i>9){
      i=0;
    }
  }
  else{
    i--;
    if(i<0){
      i=9;
    }
  }
}

//This function activates and deactivates the segments 
//so the numbers appear on the display
void sevenSegment (int selection){
  switch(selection){
  case 0:
  /* display 0
        -
       |  |
       |  |
        -
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
  digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, HIGH);  //activate segment E
    digitalWrite(F_pin, HIGH);  //activate segment F
    digitalWrite(G_pin, LOW);   //deactivate segment G
    break;
    
  case 1:
 /* display 1
      
         |
         |
        
    */
  digitalWrite(A_pin, LOW);   //deactivate segment A
  digitalWrite(B_pin, HIGH);  //activate segment B
  digitalWrite(C_pin, HIGH);  //activate segment C
  digitalWrite(D_pin, LOW);   //deactivate segment D
  digitalWrite(E_pin, LOW);   //deactivate segment E
    digitalWrite(F_pin, LOW);     //deactivate segment F
    digitalWrite(G_pin, LOW);   //deactivate segment G
    break;
    
  case 2:
  /* display 2
        -
         |
        -
       | 
        -
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, LOW);     //deactivate segment C
    digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, HIGH);  //activate segment E
    digitalWrite(F_pin, LOW);   //deactivate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
    
  case 3:
  /* display 3
        -
         |
        -
         | 
        -
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, LOW);   //deactivate segment E
    digitalWrite(F_pin, LOW);   //deactivate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
    
  case 4:
  /* display 4
      
       | |
        -
         | 
        
    */
    digitalWrite(A_pin, LOW);   //deactivate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
  digitalWrite(D_pin, LOW);   //deactivate segment D
    digitalWrite(E_pin, LOW);   //deactivate segment E
    digitalWrite(F_pin, HIGH);    //activate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
    
  case 5:
  /* display 5
        -
       | 
        -
         | 
        -
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, LOW);     //deactivate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, LOW);   //deactivate segment E
    digitalWrite(F_pin, HIGH);  //activate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G  
    break;
    
  case 6:
  /* display 6
      
       | 
        -
       |  | 
        -
    */
    digitalWrite(A_pin, LOW);   //deactivate segment A
    digitalWrite(B_pin, LOW);   //deactivate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, HIGH);  //activate segment E
    digitalWrite(F_pin, HIGH);    //activate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
    
  case 7:
  /* display 7
       _
         |
         | 
        
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, LOW);   //deactivate segment D
    digitalWrite(E_pin, LOW);   //deactivate segment E
    digitalWrite(F_pin, LOW);   //deactivate segment F
    digitalWrite(G_pin, LOW);   //deactivate segment G
    break;
    
  case 8:
  /* display 8
        -
       |  |
        -
       |  |
        -
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, HIGH);  //activate segment D
    digitalWrite(E_pin, HIGH);  //activate segment E
    digitalWrite(F_pin, HIGH);    //activate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
    
  case 9:
  /* display 9
        -
       |  |
        -
          |
         
    */
    digitalWrite(A_pin, HIGH);  //activate segment A
    digitalWrite(B_pin, HIGH);  //activate segment B
    digitalWrite(C_pin, HIGH);  //activate segment C
    digitalWrite(D_pin, LOW);   //deactivate segment D
    digitalWrite(E_pin, LOW);     //deactivate segment E
    digitalWrite(F_pin, HIGH);  //activate segment F
    digitalWrite(G_pin, HIGH);  //activate segment G
    break;
  }
}