light-follower.ino

#define DEBUG
const int speedPin_M1 = 5;     //M1 Speed Control
const int speedPin_M2 = 6;     //M2 Speed Control
const int directionPin_M1 = 4;     //M1 Direction Control
const int directionPin_M2 = 7;     //M1 Direction Control
const int LDR0 = A0;            // LDR sensor to GND and 1k to 1k resistor
const int LDR1 = A1;             // LDR sensor to GND and 1k to 1k resistor

const int slow = 30;
const int fast = 120;

const int dark = 800;
const int bright = 150;
const int hyst = 50;

int initialLight;

void setup() {
#ifdef DEBUG
  Serial.begin(9600);
#endif
  initialLight = (analogRead(LDR0) + analogRead(LDR1) ) / 2;
}


void loop() {
  int  light0 = analogRead(LDR0);
  int  light1 = analogRead(LDR1);
#ifdef DEBUG
  Serial.print( light0 );
  Serial.print( " " );
  Serial.println( light1 );
#endif
  if ( (light0 > (initialLight + hyst)) && (light1 > (initialLight + hyst))) {
    carBack( fast, fast );
  }
  else if ( (light0 < ( initialLight - hyst)) || ( (light1 < ( initialLight - hyst)) )  ) {
    int speedMotor0 = map(light0, dark, bright, slow, fast);
    int speedMotor1 = map(light1, dark, bright, slow, fast);
    carAdvance( speedMotor0, speedMotor1);
  }
  else {
    carStop();
  }
  delay(10);
}

void carStop() {                //  Motor Stop
  digitalWrite(speedPin_M2, 0);
  digitalWrite(directionPin_M1, LOW);
  digitalWrite(speedPin_M1, 0);
  digitalWrite(directionPin_M2, LOW);
}
void carBack(int leftSpeed, int rightSpeed) {       //Move backward
  analogWrite (speedPin_M2, leftSpeed);             //PWM Speed Control
  digitalWrite(directionPin_M1, HIGH);
  analogWrite (speedPin_M1, rightSpeed);
  digitalWrite(directionPin_M2, HIGH);
}
void carAdvance(int leftSpeed, int rightSpeed) {     //Move forward
  analogWrite (speedPin_M2, leftSpeed);
  digitalWrite(directionPin_M1, LOW);
  analogWrite (speedPin_M1, rightSpeed);
  digitalWrite(directionPin_M2, LOW);
}
void carTurnLeft(int leftSpeed, int rightSpeed) {    //Turn Left
  analogWrite (speedPin_M2, leftSpeed);
  digitalWrite(directionPin_M1, LOW);
  analogWrite (speedPin_M1, rightSpeed);
  digitalWrite(directionPin_M2, HIGH);
}
void carTurnRight(int leftSpeed, int rightSpeed) {    //Turn Right
  analogWrite (speedPin_M2, leftSpeed);
  digitalWrite(directionPin_M1, HIGH);
  analogWrite (speedPin_M1, rightSpeed);
  digitalWrite(directionPin_M2, LOW);
}