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Pi4J Java Examples using the Pi4J Library
/*
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: Java Examples
* FILENAME : GpioOutputExample.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 - 2016 Pi4J
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import com.pi4j.io.gpio.*;
import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent;
import com.pi4j.io.gpio.event.GpioPinListenerDigital;
import com.pi4j.platform.Platform;
import com.pi4j.platform.PlatformAlreadyAssignedException;
import com.pi4j.platform.PlatformManager;
import com.pi4j.util.CommandArgumentParser;
import com.pi4j.util.Console;
import com.pi4j.util.ConsoleColor;
import java.util.concurrent.Future;
/**
* This example code demonstrates how to perform simple state
* control of a GPIO pin on the RaspberryPi.
*
* @author Robert Savage
*/
public class GpioOutputExample {
/**
* [ARGUMENT/OPTION "--pin (#)" | "-p (#)" ]
* This example program accepts an optional argument for specifying the GPIO pin (by number)
* to use with this GPIO listener example. If no argument is provided, then GPIO #1 will be used.
* -- EXAMPLE: "--pin 4" or "-p 0".
*
* @param args
* @throws InterruptedException
* @throws PlatformAlreadyAssignedException
*/
public static void main(String[] args) throws InterruptedException, PlatformAlreadyAssignedException {
// create Pi4J console wrapper/helper
// (This is a utility class to abstract some of the boilerplate code)
final Console console = new Console();
// print program title/header
console.title("<-- The Pi4J Project -->", "GPIO Output Example");
// allow for user to exit program using CTRL-C
console.promptForExit();
// create gpio controller
final GpioController gpio = GpioFactory.getInstance();
// by default we will use gpio pin #01; however, if an argument
// has been provided, then lookup the pin by address
Pin pin = CommandArgumentParser.getPin(
RaspiPin.class, // pin provider class to obtain pin instance from
RaspiPin.GPIO_01, // default pin if no pin argument found
args); // argument array to search in
// provision gpio pin as an output pin and turn on
final GpioPinDigitalOutput output = gpio.provisionDigitalOutputPin(pin, "My Output", PinState.HIGH);
// set shutdown state for this pin: keep as output pin, set to low state
output.setShutdownOptions(false, PinState.LOW);
// create a pin listener to print out changes to the output gpio pin state
output.addListener(new GpioPinListenerDigital() {
@Override
public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) {
// display pin state on console
console.println(" --> GPIO PIN STATE CHANGE: " + event.getPin() + " = " +
ConsoleColor.conditional(
event.getState().isHigh(), // conditional expression
ConsoleColor.GREEN, // positive conditional color
ConsoleColor.RED, // negative conditional color
event.getState())); // text to display
}
});
// prompt user that we are ready
console.println(" ... Successfully provisioned output pin: " + output.toString());
console.emptyLine();
console.box("The GPIO output pin states will cycle HIGH and LOW states now.");
console.emptyLine();
// notify user of current pin state
console.println("--> [" + output.toString() + "] state was provisioned with state = " +
ConsoleColor.conditional(
output.getState().isHigh(), // conditional expression
ConsoleColor.GREEN, // positive conditional color
ConsoleColor.RED, // negative conditional color
output.getState())); // text to display
// wait
Thread.sleep(500);
// --------------------------------------------------------------------------
// tset gpio pin state to LOW
console.emptyLine();
console.println("Setting output pin state is set to LOW.");
output.low(); // or ... output.setState(PinState.LOW);
// wait
Thread.sleep(500);
// --------------------------------------------------------------------------
// tset gpio pin state to HIGH
console.emptyLine();
console.println("Setting output pin state from LOW to HIGH.");
output.setState(PinState.HIGH); // or ... output.high();
// wait
Thread.sleep(500);
// --------------------------------------------------------------------------
// toggle the current state of gpio pin (from HIGH to LOW)
console.emptyLine();
console.println("Toggling output pin state from HIGH to LOW.");
output.toggle();
// wait
Thread.sleep(500);
// --------------------------------------------------------------------------
// pulse gpio pin state for 1 second HIGH and then return to LOW
console.emptyLine();
console.println("Pulsing output pin state HIGH for 1 second.");
output.pulse(1000, true); // set second argument to 'true' use a blocking call
Thread.sleep(50);
// --------------------------------------------------------------------------
// blink gpio pin state for 1 second between HIGH and LOW states
console.emptyLine();
console.println("Blinking output pin state between HIGH and LOW for 3 seconds with a blink rate of 250ms.");
Future future = output.blink(250, 3000);
// --------------------------------------------------------------------------
// wait for blinking to finish; we are notified in a future object
while(!future.isDone()){
Thread.sleep(50);
}
// 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();
}
}
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