Datasheet

Chapter 7 • Navigating with Infrared Headlights
236 • Robotics with the BOE Shield-Bot
Servo servoLeft; // Declare left and right servos
Servo servoRight;
void setup() // Built-in initialization block
{
pinMode(10, INPUT); pinMode(9, OUTPUT); // Left IR LED & Receiver
pinMode(3, INPUT); pinMode(2, OUTPUT); // Right IR LED & Receiver
tone(4, 3000, 1000); // Play tone for 1 second
delay(1000); // Delay to finish tone
servoLeft.attach(13); // Attach left signal to pin 13
servoRight.attach(12); // Attach right signal to pin 12
}
void loop() // Main loop auto-repeats
{
int irLeft = irDetect(9, 10, 38000); // Check for object on left
int irRight = irDetect(2, 3, 38000); // Check for object on right
if((irLeft == 0) && (irRight == 0)) // If both sides detect
{
maneuver(-200, -200, 20); // Backward 20 milliseconds
}
else if(irLeft == 0) // If only left side detects
{
maneuver(200, -200, 20); // Right for 20 ms
}
else if(irRight == 0) // If only right side detects
{
maneuver(-200, 200, 20); // Left for 20 ms
}
else // Otherwise, no IR detects
{
maneuver(200, 200, 20); // Forward 20 ms
}
}
int irDetect(int irLedPin, int irReceiverPin, long frequency)
{
tone(irLedPin, frequency, 8); // IRLED 38 kHz for at least 1 ms
delay(1); // Wait 1 ms
int ir = digitalRead(irReceiverPin); // IR receiver -> ir variable
delay(1); // Down time before recheck
return ir; // Return 1 no detect, 0 detect
}
void maneuver(int speedLeft, int speedRight, int msTime)
{
// speedLeft, speedRight ranges: Backward Linear Stop Linear Forward
// -200 -100....0.....100 200
servoLeft.writeMicroseconds(1500 + speedLeft); // Left servo speed