Datasheet

Light-Sensitive Navigation with Phototransistors • Chapter 6
Robotics with the BOE Shield-Bot • 207
Activity 5: Shield-Bot Navigating by Light
At this point, the LightSeekingDisplay sketch needs four things to take it from displaying
what it’s going to do to actually doing it:
 Remove the
Serial.print calls.
 Add servo code.
 Add the
maneuver function.
 Add a call to the
loop function to pass speedLeft and speedRight to
the
maneuver function.
The result is the LightSeekingShieldBot sketch.
 Create, save, and run the sketch LightSeekingShieldBot.
 Connect the battery pack, put the BOE Shield-Bot on the floor, and set the power
switch to 2.
 Let the BOE Shield-Bot roam and try casting shadows over its left and right light
sensors. It should turn away from the shadow.
/*
* Robotics with the BOE Shield - LightSeekingShieldBot
* Roams toward light and away from shade.
*/
#include <Servo.h> // Include servo library
Servo servoLeft; // Declare left and right servos
Servo servoRight;
void setup() // Built-in initialization block
{
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
{
float tLeft = float(rcTime(8)); // Get left light & make float
float tRight = float(rcTime(6)); // Get right light & make float
float ndShade; // Normalized differential shade
ndShade = tRight / (tLeft+tRight) - 0.5; // Calculate & subtract 0.5
int speedLeft, speedRight; // Declare speed variables
if (ndShade > 0.0) // Shade on right?
{ // Slow down left wheel