#include <SoftwareSerial.h>

SoftwareSerial mySerial(4, 3); // RX, TX

const int m1a = 6; //upper left 1st motor
const int m1b = 7;
const int m2a = 8; //upper right 2nd motor
const int m2b = 9;
const int m3a = 10; //lower left 3rd motor
const int m3b = 12;
const int m4a = 13; //lower right 4th motor
const int m4b = A0;
const int m1P = 5; //Enable PWM pin for 1st motor
const int m2P = 11;  //Enable PWM pin for 2nd motor
//const int m3P = 6;  //Enable PWM pin for 3rd motor
//const int m4P = 4;  //Enable PWM pin for 4th motor

int i = 0;

char data;

void setup() {
  Serial.begin(9600); 
 mySerial.begin(9600); //initialize serial @ 9600 baudrate
  pinMode(m1a, OUTPUT);  //defining pins
  pinMode(m1b, OUTPUT);
  pinMode(m2a, OUTPUT);
  pinMode(m2b, OUTPUT);
  pinMode(m3a, OUTPUT);
  pinMode(m3b, OUTPUT);
  pinMode(m4a, OUTPUT);
  pinMode(m4b, OUTPUT);

  }

void loop() {

  //if serial value is received
  while (mySerial.available() > 0) 
  {
    //save it to character 'data'
    data = mySerial.read();
    //print it on serial monitor
    Serial.println(data);
    //if 'F' is recieved go forward
    if (data == 'F' && i != 1)
    {
      //at full speed
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
      
      digitalWrite(m1a, HIGH);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, HIGH);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, HIGH);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, HIGH);
      digitalWrite(m4b, LOW);
    }
    //backward
    if (data == 'B' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);

      digitalWrite(m1a, LOW);
      digitalWrite(m1b, HIGH);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, HIGH);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, HIGH);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, HIGH);
    }
    //left
    if (data == 'L' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
      
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, HIGH);
      digitalWrite(m2a, HIGH);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, HIGH);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, HIGH);
    }
    //right
    if (data == 'R' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
     
      digitalWrite(m1a, HIGH);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, HIGH);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, HIGH);
      digitalWrite(m4a, HIGH);
      digitalWrite(m4b, LOW);
    }
    //forward left
    if (data == 'G' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
      
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, HIGH);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, HIGH);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, LOW);
    }
    //forward right
    if (data == 'I' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
      
      digitalWrite(m1a, HIGH);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, HIGH);
      digitalWrite(m4b, LOW);
    }
    //backward left
    if (data == 'H' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
     
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, HIGH);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, HIGH);
    }
    //backward right
    if (data == 'J' && i != 1)
    {
      analogWrite(m1P, 255);
      analogWrite(m2P, 255);
      
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, HIGH);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, HIGH);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, LOW);
    }
    //stop
    if ((data == 'S' || data == 'D') && i != 1)
    {
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, LOW);
    }
    //counter clockwise
    if (data == '0' || data == '1' || data == '2' || data == '3')
    {
      //at medium speed
      analogWrite(m1P, 150);
      analogWrite(m2P, 150);
      
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, HIGH);
      digitalWrite(m2a, HIGH);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, HIGH);
      digitalWrite(m4a, HIGH);
      digitalWrite(m4b, LOW);
      i = 1;
    }
    //neutral
    if (data == '4' || data == '5' || data == '6')
    {
      digitalWrite(m1a, LOW);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, LOW);
      digitalWrite(m3a, LOW);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, LOW);
      i = 0;
    }
    //clockwise
    if (data == '7' || data == '8' || data == '9' || data == 'q')
    {
      i = 1;
      analogWrite(m1P, 150);
      analogWrite(m2P, 150);
      
      Serial.println("CLOCKWISE");
      digitalWrite(m1a, HIGH);
      digitalWrite(m1b, LOW);
      digitalWrite(m2a, LOW);
      digitalWrite(m2b, HIGH);
      digitalWrite(m3a, HIGH);
      digitalWrite(m3b, LOW);
      digitalWrite(m4a, LOW);
      digitalWrite(m4b, HIGH);

    }
    
  }
}