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Pi4J Library Plugin for Linux File System I/O Providers
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package com.pi4j.plugin.linuxfs.internal;
/*-
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: PLUGIN :: LinuxFS I/O Providers
* FILENAME : LinuxGpio.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.io.gpio.digital.DigitalState;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
/**
* LinuxGpio class.
*
* @see "https://www.kernel.org/doc/Documentation/gpio/sysfs.txt"
* @author Robert Savage (http://www.savagehomeautomation.com)
* @version $Id: $Id
*/
public class LinuxGpio {
/** Constant DEFAULT_SYSTEM_PATH="/sys/class/gpio" */
public static String DEFAULT_SYSTEM_PATH = "/sys/class/gpio";
protected final String systemPath;
protected final int address;
protected final String pinPath;
public enum Direction{
IN,
OUT,
UNKNOWN
}
public enum Edge{
NONE,
RISING,
FALLING,
BOTH,
UNKNOWN
}
/**
* Constructor for LinuxGpio.
*
* @param systemPath a {@link java.lang.String} object.
* @param address a int.
*/
public LinuxGpio(String systemPath, int address){
this.address = address;
this.systemPath = systemPath;
this.pinPath = Paths.get(systemPath, String.format("gpio%d", address)).toString();
}
/**
* Constructor for LinuxGpio.
*
* @param address a int.
*/
public LinuxGpio(int address){
this(DEFAULT_SYSTEM_PATH, address);
}
/**
* Export GPIO pin by SoC address
*
* @throws java.io.IOException if any.
*/
public void export() throws IOException {
var path = Paths.get(systemPath, "export");
Files.writeString(path, Integer.toString(address));
}
/**
* unexport.
*
* @throws java.io.IOException if any.
*/
public void unexport() throws IOException {
var path = Paths.get(systemPath, "unexport");
Files.writeString(path, Integer.toString(address));
}
/**
* isExported.
*
* @return a boolean.
* @throws java.io.IOException if any.
*/
public boolean isExported() throws IOException {
return Files.exists(Paths.get(pinPath));
}
/**
* isInterruptSupported.
*
* @return a boolean.
* @throws java.io.IOException if any.
*/
public boolean isInterruptSupported() throws IOException {
return Files.exists(Paths.get(pinPath, "edge"));
}
/**
* direction.
*
* @param direction a {@link LinuxGpio.Direction} object.
* @throws java.io.IOException if any.
*/
public void direction(Direction direction) throws IOException {
setDirection(direction);
}
/**
* setDirection.
*
* @param direction a {@link LinuxGpio.Direction} object.
* @throws java.io.IOException if any.
*/
public void setDirection(Direction direction) throws IOException {
var path = Paths.get(pinPath, "direction");
Files.writeString(path, direction.name().toLowerCase());
}
/**
* direction.
*
* @return a {@link LinuxGpio.Direction} object.
* @throws java.io.IOException if any.
*/
public Direction direction() throws IOException {
return getDirection();
}
/**
* getDirection.
*
* @return a {@link LinuxGpio.Direction} object.
* @throws java.io.IOException if any.
*/
public Direction getDirection() throws IOException {
var path = Paths.get(pinPath, "direction");
switch(Files.readString(path).trim().toLowerCase()){
case "in": return Direction.IN;
case "out": return Direction.OUT;
default: return Direction.UNKNOWN;
}
}
/**
* state.
*
* @param state a {@link com.pi4j.io.gpio.digital.DigitalState} object.
* @throws java.io.IOException if any.
*/
public void state(DigitalState state) throws IOException {
setState(state);
}
/**
* setState.
*
* @param state a {@link com.pi4j.io.gpio.digital.DigitalState} object.
* @throws java.io.IOException if any.
*/
public void setState(DigitalState state) throws IOException {
var path = Paths.get(pinPath,"value");
Files.writeString(path, (state.isHigh() ? "1" : "0"));
}
/**
* state.
*
* @return a {@link com.pi4j.io.gpio.digital.DigitalState} object.
* @throws java.io.IOException if any.
*/
public DigitalState state() throws IOException {
return getState();
}
/**
* getState.
*
* @return a {@link com.pi4j.io.gpio.digital.DigitalState} object.
* @throws java.io.IOException if any.
*/
public DigitalState getState() throws IOException {
var path = Paths.get(pinPath,"value");
return DigitalState.parse(Files.readString(path).trim());
}
/**
* interruptEdge.
*
* @param edge a {@link LinuxGpio.Edge} object.
* @throws java.io.IOException if any.
*/
public void interruptEdge(Edge edge) throws IOException {
setInterruptEdge(edge);
}
/**
* setInterruptEdge.
*
* @param edge a {@link LinuxGpio.Edge} object.
* @throws java.io.IOException if any.
*/
public void setInterruptEdge(Edge edge) throws IOException {
var path = Paths.get(pinPath, "edge");
Files.writeString(path, edge.name().toLowerCase());
}
/**
* interruptEdge.
*
* @return a {@link LinuxGpio.Edge} object.
* @throws java.io.IOException if any.
*/
public Edge interruptEdge() throws IOException {
return getInterruptEdge();
}
/**
* getInterruptEdge.
*
* @return a {@link LinuxGpio.Edge} object.
* @throws java.io.IOException if any.
*/
public Edge getInterruptEdge() throws IOException {
var path = Paths.get(pinPath, "edge");
switch(Files.readString(path).trim().toLowerCase()){
case "none": return Edge.NONE;
case "rising": return Edge.RISING;
case "falling": return Edge.FALLING;
case "both": return Edge.BOTH;
default: return Edge.UNKNOWN;
}
}
/**
* activeLow.
*
* @param enabled a boolean.
* @throws java.io.IOException if any.
*/
public void activeLow(boolean enabled) throws IOException {
setActiveLow(enabled);
}
/**
* setActiveLow.
*
* @param enabled a boolean.
* @throws java.io.IOException if any.
*/
public void setActiveLow(boolean enabled) throws IOException {
var path = Paths.get(pinPath,"active_low");
Files.writeString(path, (enabled ? "1" : "0"));
}
/**
* activeLow.
*
* @return a boolean.
* @throws java.io.IOException if any.
*/
public boolean activeLow() throws IOException {
return getActiveLow();
}
/**
* getActiveLow.
*
* @return a boolean.
* @throws java.io.IOException if any.
*/
public boolean getActiveLow() throws IOException {
var path = Paths.get(pinPath,"active_low");
return Files.readString(path).trim().equalsIgnoreCase("1");
}
/**
* Get Linux File System path for GPIO
* @return Linux File System path for GPIO
*/
public String systemPath(){
return getSystemPath();
}
/**
* Get Linux File System path for GPIO
* @return Linux File System path for GPIO
*/
public String getSystemPath(){
return this.systemPath;
}
/**
* Get Linux File System path for this GPIO pin instance
* @return Linux File System path for this GPIO pin instance
*/
public String pinPath(){
return getPinPath();
}
/**
* Get Linux File System path for this GPIO pin instance
* @return Linux File System path for this GPIO pin instance
*/
public String getPinPath(){
return this.pinPath;
}
}