Merge pull request #177 from EAGrahamJr/servo-factory

Create a simple wrapper/factory for "servo hats"

diozero-core/src/main/java/com/diozero/devices/ServoController.java

@@ -0,0 +1,153 @@
+package com.diozero.devices;
+
+/*
+ * #%L
+ * Organisation: diozero
+ * Project: diozero - Core
+ * Filename: ServoController.java
+ *
+ * This file is part of the diozero project. More information about this project
+ * can be found at https://www.diozero.com/.
+ * %%
+ * Copyright (C) 2016 - 2023 diozero
+ * %%
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ * #L%
+ */
+
+import java.util.Objects;
+
+import com.diozero.api.ServoDevice;
+import com.diozero.api.ServoTrim;
+
+/**
+ * A "wrapper" around the PCA9685 PWM controller: the main purpose is to prevent re-use of a previously allocated PWM
+ * channel.
+ * <p>
+ * <b>NOTEL</b> The servo creation allows for setting the initial angle of the servo (aka `initialPulseWidthUs`). This
+ * is <i>intended</i> to prevent the servo from "jumping" to the default position when the servo is first powered on.
+ * </p>
+ */
+public class ServoController implements AutoCloseable {
+ private final PCA9685 pwmController;
+ private final ServoDevice[] servos = new ServoDevice[16];
+
+ /**
+ * Default constructor. Uses the default PCA9685 controller.
+ */
+ public ServoController() {
+ this(new PCA9685());
+ }
+
+ /**
+ * Constructor.
+ *
+ * @param controller the PCA9685 controller to use
+ */
+ public ServoController(PCA9685 controller) {
+ pwmController = controller;
+ }
+
+ // implement singleton pattern
+ private static ServoController instance;
+
+ /**
+ * Get the singleton <b>default</b> instance of the ServoController.
+ *
+ * @return the default ServoController
+ */
+ public static synchronized ServoController getInstance() {
+ if (instance == null) {
+ instance = new ServoController();
+ }
+ return instance;
+ }
+
+ @Override
+ public void close() throws Exception {
+ pwmController.close();
+ }
+
+ /**
+ * Get a ServoDevice for the specified channel. If the channel has not been used before, a new ServoDevice will be
+ * created. If the channel has been used before, the existing ServoDevice will be returned. This will use the default
+ * trim and the initial angle <b>should</b> be 90 degrees.
+ *
+ * @param servoNumber 0-15
+ * @return the appropriate ServoDevice
+ */
+ public ServoDevice getServo(int servoNumber) {
+ return createOrGetServo(servoNumber, ServoTrim.DEFAULT, null);
+ }
+
+ /**
+ * Get a ServoDevice for the specified servo. If the servo has not been used before, a new ServoDevice will be
+ * created. If it has been used before, the existing ServoDevice will be returned. This will use the default trim.
+ *
+ * @param servoNumber 0-15
+ * @param startAngle the initial angle
+ * @return the appropriate ServoDevice
+ */
+ public ServoDevice getServo(int servoNumber, int startAngle) {
+ return getServo(servoNumber, ServoTrim.DEFAULT, startAngle);
+ }
+
+ /**
+ * Get a ServoDevice for the specified servo. If the servo has not been used before, a new ServoDevice will be
+ * created. If it has been used before, the existing ServoDevice will be returned. The initial angle <b>should</b>
+ * be 90 degrees.
+ *
+ * @param servoNumber 0-15
+ * @param trim Servo trim
+ * @return the appropriate ServoDevice
+ */
+ public ServoDevice getServo(int servoNumber, ServoTrim trim) {
+ return createOrGetServo(servoNumber, trim, null);
+ }
+
+ /**
+ * Get a ServoDevice for the specified servo. If the servo has not been used before, a new ServoDevice will be
+ * created. If it has been used before, the existing ServoDevice will be returned.
+ * <p>
+ * NOTE: {@code trim} and {@code startAngle} will only be applied on device creation.
+ * </p>
+ *
+ * @param servoNumber 0-15
+ * @param trim Servo trim
+ * @param startAngle the initial angle
+ * @return the appropriate ServoDevice
+ */
+ public ServoDevice getServo(int servoNumber, ServoTrim trim, int startAngle) {
+ return createOrGetServo(servoNumber, trim, trim.convertAngleToPulseWidthUs(startAngle));
+ }
+
+ private synchronized ServoDevice createOrGetServo(int servoNumber, ServoTrim trim, Integer initialPulseWidthUs) {
+ Objects.checkIndex(servoNumber, 16);
+
+ if (servos[servoNumber] == null) {
+ servos[servoNumber] = new ServoDevice.Builder(servoNumber)
+ .setDeviceFactory(pwmController)
+ .setTrim(trim)
+ .setFrequency(pwmController.getBoardPwmFrequency())
+ .setInitialPulseWidthUs(initialPulseWidthUs)
+ .build();
+ }
+ return servos[servoNumber];
+ }
+}