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Pi4J Java Examples using the Pi4J Library
package bananapi;
/*
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: Java Examples
* FILENAME : GpioListenAllExample.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;
/**
* This example code demonstrates how to setup a listener
* for GPIO pin state changes on the BananaPi.
*
* @author Robert Savage
*/
public class GpioListenAllExample {
/**
* [ARGUMENT/OPTION "--pull (up|down|off)" | "-l (up|down|off)" | "--up" | "--down" ]
* This example program accepts an optional argument for specifying pin pull resistance.
* Supported values: "up|down" (or simply "1|0"). If no value is specified in the command
* argument, then the pin pull resistance will be set to PULL_UP by default.
* -- EXAMPLES: "--pull up", "-pull down", "--pull off", "--up", "--down", "-pull 0", "--pull 1", "-l up", "-l down".
*
* @param args
* @throws InterruptedException
* @throws PlatformAlreadyAssignedException
*/
public static void main(String args[]) throws InterruptedException, PlatformAlreadyAssignedException {
// ####################################################################
//
// since we are not using the default Raspberry Pi platform, we should
// explicitly assign the platform as the BananaPi platform.
//
// ####################################################################
PlatformManager.setPlatform(Platform.BANANAPI);
// 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 Listen (All Pins) Example");
// allow for user to exit program using CTRL-C
console.promptForExit();
// create GPIO controller
final GpioController gpio = GpioFactory.getInstance();
// create GPIO listener
GpioPinListenerDigital listener = new GpioPinListenerDigital() {
@Override
public void handleGpioPinDigitalStateChangeEvent(GpioPinDigitalStateChangeEvent event) {
// display pin state on console
console.println(" --> GPIO PIN STATE CHANGE (EVENT): " + event.getPin() + " = " +
ConsoleColor.conditional(
event.getState().isHigh(), // conditional expression
ConsoleColor.GREEN, // positive conditional color
ConsoleColor.RED, // negative conditional color
event.getState())); // text to display
}
};
// by default we will use gpio pin PULL-UP; however, if an argument
// has been provided, then use the specified pull resistance
PinPullResistance pull = CommandArgumentParser.getPinPullResistance(
PinPullResistance.PULL_UP, // default pin pull resistance if no pull argument found
args); // argument array to search in
// prompt user to wait
console.println(" ... please wait; provisioning GPIO pins with resistance [" + pull + "]");
// ####################################################################
//
// When provisioning a pin, use the BananaPiPin class.
//
// Please note that not all GPIO pins support edge triggered interrupts
// and thus not all pins are eligible for pin state change listeners.
// These pins must be polled to detect state changes.
//
// An example of pins that support interrupt listeners as well as pins
// that support only polling are included below.
//
// ####################################################################
// provision gpio input pins with its internal pull down resistor set
GpioPinDigitalInput[] event_pins = {
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_00, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_01, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_02, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_03, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_04, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_05, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_06, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_10, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_11, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_12, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_13, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_14, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_15, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_16, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_17, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_19, pull),
};
// create and register gpio pin listeners
gpio.addListener(listener, event_pins);
// these pins must be polled for input state changes, these pins do not support edge detection and/or interrupts
// provision gpio input pins with its internal pull resistors configured
GpioPinDigitalInput[] polled_pins = {
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_07, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_08), // I2C pin permanently pulled up
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_09), // I2C pin permanently pulled up
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_18, pull),
gpio.provisionDigitalInputPin(BananaPiPin.GPIO_20, pull),
};
// unexport the provisioned GPIO pins when program exits
gpio.setShutdownOptions(true, event_pins);
gpio.setShutdownOptions(true, polled_pins);
// prompt user that we are ready
console.println(" ... GPIO pins provisioned and ready for use.");
console.emptyLine();
console.box("Please complete the GPIO circuit and see",
"the listener feedback here in the console.");
console.emptyLine();
// cache the current state of the polled pins
for(GpioPinDigitalInput pin : polled_pins){
pin.setProperty("last_known_state", pin.getState().name());
}
// keep program running until user aborts (CTRL-C)
while(console.isRunning()) {
Thread.sleep(50);
// poll pin states looking for pin state changes
for(GpioPinDigitalInput pin : polled_pins){
if(!pin.getState().name().equals(pin.getProperty("last_known_state"))){
// display pin state on console
console.println(" --> GPIO PIN STATE CHANGE (POLLED): " + pin + " = " +
ConsoleColor.conditional(
pin.getState().isHigh(), // conditional expression
ConsoleColor.GREEN, // positive conditional color
ConsoleColor.RED, // negative conditional color
pin.getState())); // text to display
// update last known state cached value
pin.setProperty("last_known_state", pin.getState().name());
}
}
}
// 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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