bluetotth_car_arduino.ino

// Arduino pins for the shift register
#define MOTORLATCH 12
#define MOTORCLK 4
#define MOTORENABLE 7
#define MOTORDATA 8

// Arduino pins for the PWM signals.
#define MOTOR1_PWM 11
#define MOTOR2_PWM 3
#define MOTOR3_PWM 6
#define MOTOR4_PWM 5
#define SERVO1_PWM 10
#define SERVO2_PWM 9


// 8-bit bus after the 74HC595 shift register 
// (not Arduino pins)
// These are used to set the direction of the bridge driver.
#define MOTOR1_A 2
#define MOTOR1_B 3
#define MOTOR2_A 1
#define MOTOR2_B 4
#define MOTOR3_A 5
#define MOTOR3_B 7
#define MOTOR4_A 0
#define MOTOR4_B 6 

// Codes for the motor function.
#define FORWARD 1
#define BACKWARD 2
#define LEFT 5
#define RIGHT 6
#define LIGHTS_ON 7
#define LIGHTS_OFF 8
#define BRAKE 3
#define RELEASE 4

char val; // value that comes from outside

void setup()
{
  Serial.begin(9600);
}


void loop()
{ 
  performCommand(); 
}


void performCommand(){
  if (Serial.available()) {
    val = Serial.read();
    Serial.print(val);
  }
  
    if (val == 'f') { 
        motor(1, FORWARD, 255);
        
    }else if(val == 'b'){
        motor(1, BACKWARD, 255); 
        
    }else if(val == 'l'){
        motor(2, LEFT, 255); 
        
    }else if(val == 'r'){
        motor(2, RIGHT, 255); 
        
    }else if(val == 'a'){
        motor(3, LIGHTS_ON, 255); 
        
    }else if(val == 'p'){
        motor(3, LIGHTS_OFF, 255); 
        
    }else if(val == 'e'){ 
        motor(1, RELEASE, 0); 
        motor(2, RELEASE, 0); 
    }else if(val == 's'){ 
        motor(1, BRAKE, 0); 
        motor(2, BRAKE, 0); 
        motor(3, BRAKE, 0); 
    }
}

//
void motor(int nMotor, int command, int speed)
{
  int motorA, motorB;

  if (nMotor >= 1 && nMotor <= 4)
  {  
    switch (nMotor)
    {
    case 1:
      motorA   = MOTOR1_A;
      motorB   = MOTOR1_B;
      break;
    case 2:
      motorA   = MOTOR2_A;
      motorB   = MOTOR2_B;
      break;
    case 3:
      motorA   = MOTOR3_A;
      motorB   = MOTOR3_B;
      break;
    case 4:
      motorA   = MOTOR4_A;
      motorB   = MOTOR4_B;
      break;
    default:
      break;
    }

    switch (command)
    {
    case FORWARD:
      motor_output (motorA, HIGH, speed);
      motor_output (motorB, LOW, -1);     // -1: no PWM set
      break;
    case BACKWARD:
      motor_output (motorA, LOW, speed);
      motor_output (motorB, HIGH, -1);    // -1: no PWM set
      break;
    case LEFT:
      motor_output (motorA, HIGH, speed);
      motor_output (motorB, LOW, -1);     // -1: no PWM set
      break;
    case RIGHT:
      motor_output (motorA, LOW, speed);
      motor_output (motorB, HIGH, -1);    // -1: no PWM set
      break;
    case LIGHTS_ON:
      motor_output (motorA, HIGH, speed);
      motor_output (motorB, LOW, -1);     // -1: no PWM set
      break;
    case LIGHTS_OFF:
      motor_output (motorA, LOW, speed);
      motor_output (motorB, HIGH, -1);    // -1: no PWM set
      break;
    case BRAKE:
      motor_output (motorA, LOW, 255); // 255: fully on.
      motor_output (motorB, LOW, -1);  // -1: no PWM set
      break;
    case RELEASE:
      motor_output (motorA, LOW, 0);  // 0: output floating.
      motor_output (motorB, LOW, -1); // -1: no PWM set
      break;
    default:
      break;
    }
  }
}

void motor_output (int output, int high_low, int speed)
{
  int motorPWM;

  switch (output)
  {
  case MOTOR1_A:
  case MOTOR1_B:
    motorPWM = MOTOR1_PWM;
    break;
  case MOTOR2_A:
  case MOTOR2_B:
    motorPWM = MOTOR2_PWM;
    break;
  case MOTOR3_A:
  case MOTOR3_B:
    motorPWM = MOTOR3_PWM;
    break;
  case MOTOR4_A:
  case MOTOR4_B:
    motorPWM = MOTOR4_PWM;
    break;
  default:
    // Use speed as error flag, -3333 = invalid output.
    speed = -3333;
    break;
  } 
  
 if (speed != -3333)
  {
    shiftWrite(output, high_low);

    // set PWM only if it is valid
    if (speed >= 0 && speed <= 255)    
    {
      analogWrite(motorPWM, speed);
    }
  }
}

void shiftWrite(int output, int high_low)
{
  static int latch_copy;
  static int shift_register_initialized = false;

  // Do the initialization on the fly, 
  // at the first time it is used.
  if (!shift_register_initialized)
  {
    // Set pins for shift register to output
    pinMode(MOTORLATCH, OUTPUT);
    pinMode(MOTORENABLE, OUTPUT);
    pinMode(MOTORDATA, OUTPUT);
    pinMode(MOTORCLK, OUTPUT);

    // Set pins for shift register to default value (low);
    digitalWrite(MOTORDATA, LOW);
    digitalWrite(MOTORLATCH, LOW);
    digitalWrite(MOTORCLK, LOW);
    // Enable the shift register, set Enable pin Low.
    digitalWrite(MOTORENABLE, LOW);

    // start with all outputs (of the shift register) low
    latch_copy = 0;

    shift_register_initialized = true;
  }

  bitWrite(latch_copy, output, high_low);

  shiftOut(MOTORDATA, MOTORCLK, MSBFIRST, latch_copy);
  delayMicroseconds(5);    // For safety, not really needed.
  digitalWrite(MOTORLATCH, HIGH);
  delayMicroseconds(5);    // For safety, not really needed.
  digitalWrite(MOTORLATCH, LOW);
}