FTC Programming with ElectronVolts

ColorSensor uses a red LED, a blue LED, and a photoresistor to detect the color of a line on the mat. It has 4 methods for setting the color: red, blue, magenta, and off. It implements DigitalSensor, returning whether or not it is seeing the color specified. It is used in LineFinder along with DoubleLineSensor to more accurately find colored lines.

Fun fact: last year when connecting LEDs, we guessed on the resistor values and it burnt out 2 of our digital outputs. Always calculate the current before you plug LEDs in to the Core Device Interface Module.

ftc/evlib/hardware/sensors/ColorSensor.java

package ftc.evlib.hardware.sensors;

import com.qualcomm.robotcore.hardware.LED;

/**
 * This file was made by the electronVolts, FTC team 7393
 * Date Created: 3/22/16
 * 
 * Uses LEDs and a photoresistor to detect the color of a line on the mat
 * 
 * --- light red blue
 * mat    35 250 250
 * red
 * blue
 * white 145 640 550
 *
 * @see DigitalSensor
 */
public class ColorSensor implements DigitalSensor {
    private static final int THRESHOLD = 500;
    private final LED redLight, blueLight;
    private final AveragedSensor lightSensor;
    private String ledColorString = "unknown";

    /**
     * @param redLight    the red LED
     * @param blueLight   the blue LED
     * @param lightSensor the photoresistor
     */
    public ColorSensor(LED redLight, LED blueLight, AveragedSensor lightSensor) {
        this.redLight = redLight;
        this.blueLight = blueLight;
        this.lightSensor = lightSensor;
    }

    /**
     * turn off both LEDs
     */
    public void turnOff() {
        redLight.enable(true);
        blueLight.enable(true);
        ledColorString = "blank";
    }

    /**
     * turn on the red LED and turn off the blue LED
     */
    public void setColorRed() {
        redLight.enable(false);
        blueLight.enable(true);
        ledColorString = "red";
    }

    /**
     * turn on the blue LED and turn off the red LED
     */
    public void setColorBlue() {
        redLight.enable(true);
        blueLight.enable(false);
        ledColorString = "blue";
    }

    /**
     * turn on both LEDs
     */
    public void setColorMagenta() {
        redLight.enable(false);
        blueLight.enable(false);
        ledColorString = "magenta";
    }

    /**
     * @return the name of the current color for telemetry purposes
     */
    public String getLedColorString() {
        return ledColorString;
    }

    /**
     * update the light sensor
     */
    public void act() {
        lightSensor.act();
    }

    /**
     * @return true if it is seeing the color requested
     */
    @Override
    public Boolean getValue() {
        return lightSensor.getValue() > THRESHOLD;
    }

    /**
     * @return the raw value of the light sensor
     */
    public double getRawValue() {
        return lightSensor.getValue();
    }
}