Merge pull request #225 from oss-slu/issue_8

Servo Motor Implementation. Issue #8

components/src/main/java/com/opensourcewithslu/components/controllers/ServoMotorController.java

@@ -0,0 +1,34 @@
+package com.opensourcewithslu.components.controllers;
+
+import com.opensourcewithslu.outputdevices.ServoMotorHelper;
+import com.pi4j.io.pwm.Pwm;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import jakarta.inject.Named;
+
+//tag::ex[]
+@Controller("/servoMotor")
+public class ServoMotorController {
+
+    private final ServoMotorHelper servoMotorHelper;
+
+    public ServoMotorController(@Named("servo-motor")Pwm servoMotor) {
+        this.servoMotorHelper = new ServoMotorHelper(servoMotor);
+    }
+
+    @Get("/enable")
+    public void enableServoMotor() {
+        servoMotorHelper.enable();
+    }
+
+    @Get("/disable")
+    public void disableServoMotor() {
+        servoMotorHelper.disable();
+    }
+
+    @Get("/setAngle/{angle}")
+    public void setAngle(int angle) {
+        servoMotorHelper.setAngle(angle);
+    }
+}
+//end::ex[]

components/src/main/resources/application.yml

@@ -28,6 +28,13 @@ pi4j:
       provider: pigpio-pwm
       initial: 0
       shutdown: 0
+    servo-motor:
+      name: Servo Motor
+      address: 18
+      pwmType: SOFTWARE
+      provider: pigpio-pwm
+      initial: 0
+      shutdown: 0
   # end::pwm[]
 
   # tag::i2c[]

pi4micronaut-utils/src/main/java/com/opensourcewithslu/outputdevices/ServoMotorHelper.java

@@ -0,0 +1,91 @@
+package com.opensourcewithslu.outputdevices;
+
+import com.pi4j.io.pwm.Pwm;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Helper class to control a servo motor using PWM (Pulse Width Modulation).
+ * This class provides methods to enable, disable, and set the angle of a servo motor.
+ */
+public class ServoMotorHelper {
+
+    private static final Logger log = LoggerFactory.getLogger(ServoMotorHelper.class);
+    private static final int FREQUENCY = 50; // Frequency for PWM signal in Hz, typical for servo motors.
+    private static final int PWM_CYCLE_MICROSECONDS = 20000; // Total cycle length in microseconds, corresponding to 50 Hz.
+    private static final int MIN_ANGLE = 0; // Minimum angle for servo operation.
+    private static final int MAX_ANGLE = 180; // Maximum angle for servo operation.
+    private static final int SERVO_MIN_PULSE = 500; // Minimum pulse width in microseconds corresponding to 0 degrees.
+    private static final int SERVO_MAX_PULSE = 2500; // Maximum pulse width in microseconds corresponding to 180 degrees.
+    private boolean isEnabled = false; // State tracking variable for the servo motor.
+    private final Pwm servoMotor; // PWM interface for the servo motor.
+
+    /**
+     * Constructs a new ServoMotorHelper.
+     *
+     * @param servoMotor A PWM interface to control the servo motor.
+     */
+    public ServoMotorHelper(Pwm servoMotor) {
+        this.servoMotor = servoMotor;
+    }
+
+    /**
+     * Enables the servo motor by setting an initial duty cycle and frequency.
+     * The servo motor remains disabled until this method is called.
+     */
+    public void enable() {
+        log.info("Enabling servo motor");
+        servoMotor.on(0, FREQUENCY); // Initializes PWM signal with 0% duty cycle.
+        isEnabled = true;
+    }
+
+    /**
+     * Disables the servo motor, effectively stopping any ongoing PWM signal.
+     */
+    public void disable() {
+        log.info("Disabling servo motor");
+        servoMotor.off(); // Stops the PWM signal.
+        isEnabled = false;
+    }
+
+    /**
+     * Maps the given angle to the corresponding pulse width for the servo motor.
+     *
+     * @param value the angle in degrees to be mapped to pulse width.
+     * @return the calculated pulse width in microseconds.
+     */
+    private float map(float value) {
+        return SERVO_MIN_PULSE + ((value - MIN_ANGLE) * (SERVO_MAX_PULSE - SERVO_MIN_PULSE) / (MAX_ANGLE - MIN_ANGLE));
+    }
+
+    /**
+     * Sets the servo motor to a specific angle.
+     * This method calculates the necessary pulse width and duty cycle to achieve the specified angle.
+     *
+     * @param angle the target angle for the servo motor, between 0 and 180 degrees.
+     */
+    public void setAngle(int angle) {
+        if (!isEnabled) {
+            log.info("You must enable the servo motor first.");
+            return;
+        }
+
+        if (angle < MIN_ANGLE || angle > MAX_ANGLE) {
+            log.info("You must enter an angle between 0 and 180 degrees.");
+            return;
+        }
+
+        float pulseWidth = map(angle);
+        float dutyCycle = (pulseWidth / PWM_CYCLE_MICROSECONDS) * 100;
+
+        log.info("Setting servo to {} degrees, Pulse Width: {} us, Duty Cycle: {}%", angle, pulseWidth, dutyCycle);
+
+        servoMotor.on(dutyCycle, FREQUENCY);
+        try {
+            Thread.sleep(100); // Pauses the thread to allow the servo to reach the set angle.
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt(); // Properly handle thread interruption.
+            log.info("Thread was interrupted, failed to complete rotation");
+        }
+    }
+}