MultipurposePinGpioExample.java

/*
 * #%L
 * **********************************************************************
 * ORGANIZATION  :  Pi4J
 * PROJECT       :  Pi4J :: Java Examples
 * FILENAME      :  MultipurposePinGpioExample.java  
 * 
 * This file is part of the Pi4J project. More information about 
 * this project can be found here:  http://www.pi4j.com/
 * **********************************************************************
 * %%
 * Copyright (C) 2012 - 2013 Pi4J
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalMultipurpose;
import com.pi4j.io.gpio.PinMode;
import com.pi4j.io.gpio.PinPullResistance;
import com.pi4j.io.gpio.RaspiPin;
import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent;
import com.pi4j.io.gpio.event.GpioPinListenerDigital;

/**
 * This example code demonstrates how to setup a multi-purpose
 * digital pin on the Raspberry Pi.  
 * 
 * @author Robert Savage
 */
public class MultipurposePinGpioExample {
    
    public static void main(String args[]) throws InterruptedException {
    
        System.out.println("<--Pi4J--> GPIO Multipurpose Pin Example ... started.");
        
        // create gpio controller
        final GpioController gpio = GpioFactory.getInstance();

        // provision gpio pin #02 as an multi-purpose pin configured as an input  
        // pin by default with its internal pull down resistor enabled
        final GpioPinDigitalMultipurpose pin = gpio.provisionDigitalMultipurposePin(RaspiPin.GPIO_02, PinMode.DIGITAL_INPUT, PinPullResistance.PULL_DOWN);

        // create and register gpio pin listener
        pin.addListener(new GpioPinListenerDigital() {
            @Override
            public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) {
                // display pin state on console
                System.out.println(" --> GPIO PIN STATE CHANGE: " + event.getPin() + " = " + event.getState());
            }            
        });
        
        System.out.println(" ... complete the GPIO #02 circuit and see the listener feedback here in the console.");
        
        // keep program running until user aborts (CTRL-C)
        for (;;) {
            Thread.sleep(5000);

            // here we want to control the multi-purpose GPIO pin
            // so we must reconfigure the pin mode first
            pin.setMode(PinMode.DIGITAL_OUTPUT);
            
            // perform the pin output operation
            System.out.println(" --> GPIO PIN - RECONFIGURED AS OUPUT PIN");
            pin.pulse(1000, true);
            
            // reconfigure the pin back to an input pin
            pin.setMode(PinMode.DIGITAL_INPUT);
            System.out.println(" --> GPIO PIN - RECONFIGURED AS INPUT PIN");
        }
        
        // stop all GPIO activity/threads by shutting down the GPIO controller
        // (this method will forcefully shutdown all GPIO monitoring threads and scheduled tasks)
        // gpio.shutdown();   <--- implement this method call if you wish to terminate the Pi4J GPIO controller        
    }
}