for(int i = 1; i<=50; i++) // Repeat 50 times
{
Serial.print('='); // one = char each time through
}
/*
* Robotics with the BOE Shield - Chapter 6, Project 1
* Chirp when light is above threshold. Will require updating value of
* threshold & retesting under bright light to get to the right value.
*/
void setup() // Built-in initialization block
{
tone(4, 3000, 1000); // Play tone for 1 second
delay(1000); // Delay to finish tone
}
void loop() // Main loop auto-repeats
{
if(volts(A3) > 3.5) // If A3 voltage greater than 3.5
{
tone(4, 4000, 50); // Start chirping
delay(100);
}
}
float volts(int adPin) // Measures volts at adPin
{ // Returns floating point voltage
return float(analogRead(adPin)) * 5.0 / 1024.0;
}
Next, add an if statement similar to the one from HaltUnderBrightLight to the main loop of LightSeekingShieldBot. Careful though, HaltUnderBrightLight uses the greater than (>) operator because it’s using a voltage output circuit. We need the less than (<) operator for the QT circuit because smaller values mean brighter light. We also need to express the threshold as a floating point value, like 1300.0. Here’s an example:
// Add this if condition to stop under the bright lamp.
if((tRight + tLeft) < 1300.0) // tLeft+tRight < 1300?
{
servoLeft.detach(); // Stop servo signals
servoRight.detach();
}
Here’s a modified version of LightSeekingShieldBot that will do the trick. Remember, you’ll still have to calibrate it to your lighting conditions.
/*
* Robotics with the BOE Shield - Chapter 6, Project 3
* 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
// Add this if condition to stop under the bright lamp.
if((tRight + tLeft) < 1300.0) // If A3 voltage greater than 2
{
servoLeft.detach(); // Stop servo signals
servoRight.detach();
}
float ndShade; // Normalized differential shade
ndShade = tRight / (tLeft+tRight) - 0.5; // Calculate it and subtract 0.5
int speedLeft, speedRight; // Declare speed variables
if (ndShade > 0.0) // Shade on right?
{ // Slow down left wheel
speedLeft = int(200.0 - (ndShade * 1000.0));
speedLeft = constrain(speedLeft, -200, 200);
speedRight = 200; // Full speed right wheel
}
else // Shade on Left?
{ // Slow down right wheel
speedRight = int(200.0 + (ndShade * 1000.0));
speedRight = constrain(speedRight, -200, 200);
speedLeft = 200; // Full speed left wheel
}
maneuver(speedLeft, speedRight, 20); // Set wheel speeds
}
long rcTime(int pin) // rcTime measures decay at pin
{
pinMode(pin, OUTPUT); // Charge capacitor
digitalWrite(pin, HIGH); // ..by setting pin ouput-high
delay(5); // ..for 5 ms
pinMode(pin, INPUT); // Set pin to input
digitalWrite(pin, LOW); // ..with no pullup
long time = micros(); // Mark the time
while(digitalRead(pin)); // Wait for voltage < threshold
time = micros() - time; // Calculate decay time
return time; // Returns decay time
}
// maneuver function
void maneuver(int speedLeft, int speedRight, int msTime)
{
servoLeft.writeMicroseconds(1500 + speedLeft); // Set Left servo speed
servoRight.writeMicroseconds(1500 - speedRight); // Set right servo speed
if(msTime==-1) // if msTime = -1
{
servoLeft.detach(); // Stop servo signals
servoRight.detach();
}
delay(msTime); // Delay for msTime
}
