#define IR_SENSOR_RIGHT 11 #define IR_SENSOR_LEFT 12 #define MOTOR_SPEED 90

//Right motor int enableRightMotor=6; int rightMotorPin1=8; int rightMotorPin2=7;

//Left motor int enableLeftMotor=5; int leftMotorPin1=10; int leftMotorPin2=9;

void setup() { //The problem with TT gear motors is that, at very low pwm value it does not even rotate. //If we increase the PWM value then it rotates faster and our robot is not controlled in that speed and goes out of line. //For that we need to increase the frequency of analogWrite. //Below line is important to change the frequency of PWM signal on pin D5 and D6 //Because of this, motor runs in controlled manner (lower speed) at high PWM value. //This sets frequecny as 7812.5 hz. TCCR0B = TCCR0B & B11111000 | B00000010 ;

// put your setup code here, to run once: pinMode(enableRightMotor, OUTPUT); pinMode(rightMotorPin1, OUTPUT); pinMode(rightMotorPin2, OUTPUT);

pinMode(enableLeftMotor, OUTPUT); pinMode(leftMotorPin1, OUTPUT); pinMode(leftMotorPin2, OUTPUT);

pinMode(IR_SENSOR_RIGHT, INPUT); pinMode(IR_SENSOR_LEFT, INPUT); rotateMotor(0,0);
}

void loop() {

int rightIRSensorValue = digitalRead(IR_SENSOR_RIGHT); int leftIRSensorValue = digitalRead(IR_SENSOR_LEFT);

//If none of the sensors detects black line, then go straight if (rightIRSensorValue == LOW && leftIRSensorValue == LOW) { rotateMotor(MOTOR_SPEED, MOTOR_SPEED); } //If right sensor detects black line, then turn right else if (rightIRSensorValue == HIGH && leftIRSensorValue == LOW ) { rotateMotor(-MOTOR_SPEED, MOTOR_SPEED); } //If left sensor detects black line, then turn left
else if (rightIRSensorValue == LOW && leftIRSensorValue == HIGH ) { rotateMotor(MOTOR_SPEED, -MOTOR_SPEED); } //If both the sensors detect black line, then stop else { rotateMotor(0, 0); } }

void rotateMotor(int rightMotorSpeed, int leftMotorSpeed) {

if (rightMotorSpeed < 0) { digitalWrite(rightMotorPin1,LOW); digitalWrite(rightMotorPin2,HIGH);
} else if (rightMotorSpeed > 0) { digitalWrite(rightMotorPin1,HIGH); digitalWrite(rightMotorPin2,LOW);
} else { digitalWrite(rightMotorPin1,LOW); digitalWrite(rightMotorPin2,LOW);
}

if (leftMotorSpeed < 0) { digitalWrite(leftMotorPin1,LOW); digitalWrite(leftMotorPin2,HIGH);
} else if (leftMotorSpeed > 0) { digitalWrite(leftMotorPin1,HIGH); digitalWrite(leftMotorPin2,LOW);
} else { digitalWrite(leftMotorPin1,LOW); digitalWrite(leftMotorPin2,LOW);
} analogWrite(enableRightMotor, abs(rightMotorSpeed)); analogWrite(enableLeftMotor, abs(leftMotorSpeed));
}