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Pi4J Library Plugin for Linux File System I/O Providers
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package com.pi4j.plugin.linuxfs.provider.gpio.digital;
/*-
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: PLUGIN :: LinuxFS I/O Providers
* FILENAME : LinuxFsDigitalOutput.java
*
* This file is part of the Pi4J project. More information about
* this project can be found here: https://pi4j.com/
* **********************************************************************
*
* 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.context.Context;
import com.pi4j.exception.InitializeException;
import com.pi4j.exception.ShutdownException;
import com.pi4j.io.exception.IOException;
import com.pi4j.io.gpio.digital.*;
import com.pi4j.plugin.linuxfs.internal.LinuxGpio;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* LinuxFsDigitalOutput class.
*
* @author Robert Savage (http://www.savagehomeautomation.com)
* @version $Id: $Id
*/
public class LinuxFsDigitalOutput extends DigitalOutputBase implements DigitalOutput {
protected final LinuxGpio gpio;
private Logger logger = LoggerFactory.getLogger(this.getClass());
/**
* Constructor for LinuxFsDigitalOutput.
*
* @param gpio a {@link LinuxGpio} linux file system GPIO object.
* @param provider a {@link com.pi4j.io.gpio.digital.DigitalOutputProvider} object.
* @param config a {@link com.pi4j.io.gpio.digital.DigitalOutputConfig} object.
*/
public LinuxFsDigitalOutput(LinuxGpio gpio, DigitalOutputProvider provider, DigitalOutputConfig config){
super(provider, config);
this.gpio = gpio;
}
@Override
public DigitalOutput initialize(Context context) throws InitializeException {
logger.trace("initializing GPIO [{}]; {}", this.config.address(), gpio.getPinPath());
// [EXPORT] requested GPIO pin if its not already exported
try {
if(!gpio.isExported()) {
logger.trace("exporting GPIO [{}]; {}", this.config.address(), gpio.getPinPath());
gpio.export();
} else{
logger.trace("GPIO [{}] is already exported; {}", this.config.address(), gpio.getPinPath());
}
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new InitializeException("Unable to export GPIO [" + config.address() + "] @ <" + gpio.systemPath() + ">; " + e.getMessage(), e);
}
// [OUTPUT] configure GPIO pin direction as digital output
try {
logger.trace("set direction [OUT] on GPIO {}", gpio.getPinPath());
gpio.direction(LinuxGpio.Direction.OUT);
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new InitializeException("Unable to set GPIO [" + config.address() + "] DIRECTION=[OUT] @ <" + gpio.pinPath() + ">; " + e.getMessage(), e);
}
// [INTERRUPT] enable GPIO interrupt via Linux File System (if supported)
try {
if (gpio.isInterruptSupported()) gpio.interruptEdge(LinuxGpio.Edge.BOTH);
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new InitializeException("Unable to set GPIO [" + config.address() + "] INTERRUPT EDGE=[BOTH] @ <" + gpio.pinPath() + ">; " + e.getMessage(), e);
}
// [INITIALIZE STATE] initialize GPIO pin state (via superclass impl)
super.initialize(context);
// return this instance
return this;
}
/** {@inheritDoc} */
@Override
public DigitalOutput shutdown(Context context) throws ShutdownException {
logger.trace("shutdown GPIO [{}]; {}", this.config.address(), gpio.getPinPath());
// --------------------------------------------------------------------------
// [ATTENTION]
// --------------------------------------------------------------------------
// IF WE UN-EXPORT THE PIN, ANY SHUTDOWN STATE WILL BE IGNORED AND
// THE PIN WILL DEFAULT TO A LOW STATE OR POTENTIALLY A FLOATING STATE
// IF THE PIN IS DEFAULTED AS AN INPUT PIN AS A RESULT OF UN-EXPORTING IT.
//
// IF A VALID SHUTDOWN STATE HAS BEEN CONFIGURED FOR THIS DIGITAL OUTPUT INSTANCE,
// WE WILL LEAVE THE GPIO PIN EXPORTED ON SHUTDOWN OF PI4J
//
// IF NO SHUTDOWN STATE HAS BEEN CONFIGURED FOR THIS DIGITAL OUTPUT INSTANCE,
// WE WILL UN-EXPORT THE GPIO PIN ON SHUTDOWN OF PI4J
//
// (this was the same behavior in Pi4J v1.x)
// --------------------------------------------------------------------------
// set pin state to shutdown state if a shutdown state is configured
if(config().shutdownState() != null && config().shutdownState() != DigitalState.UNKNOWN){
return super.shutdown(context);
}
// otherwise ... un-export the GPIO pin from the Linux file system impl
try {
logger.trace("un-exporting GPIO [{}]; {}", this.config.address(), gpio.getPinPath());
gpio.unexport();
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new ShutdownException("Failed to UN-EXPORT GPIO [" + config().address() + "] @ <" + gpio.systemPath() + ">; " + e.getMessage(), e);
}
// return this digital output instance
return this;
}
/** {@inheritDoc} */
@Override
public DigitalOutput state(DigitalState state) throws IOException {
logger.trace("set state [{}] on GPIO [{}]; {}", state.getName(), this.config.address(), gpio.getPinPath());
try {
// apply requested GPIO state via Linux FS
gpio.state(state);
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new IOException(e.getMessage(), e);
}
return super.state(state);
}
@Override
public DigitalState state() {
logger.trace("get state on GPIO [{}]; {}", this.config.address(), gpio.getPinPath());
try {
// acquire actual GPIO state directly from Linux file system impl
DigitalState currentState = gpio.state();
// update/sync internal state tracking variable if mismatch
if(this.state != currentState) {
this.state = currentState;
logger.trace("state mismatch detected; sync internal state [{}] on GPIO [{}]; {}",
this.state.getName(),
this.config.address(),
gpio.getPinPath());
}
} catch (java.io.IOException e) {
logger.error(e.getMessage(), e);
throw new IOException(e.getMessage(), e);
}
// return current GPIO state via superclass impl
return super.state();
}
}