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Pi4J Library Plugin for Linux File System I/O Providers
package com.pi4j.plugin.linuxfs.internal;
/*-
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: PLUGIN :: LinuxFS I/O Providers
* FILENAME : LinuxPwm.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 java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
/**
* LinuxPwm class.
*
* @see "https://www.kernel.org/doc/html/latest/driver-api/pwm.html"
* @author Robert Savage (http://www.savagehomeautomation.com)
* @version $Id: $Id
*/
public class LinuxPwm {
/** Constant DEFAULT_SYSTEM_PATH="/sys/class/pwm" */
public static String DEFAULT_SYSTEM_PATH = "/sys/class/pwm";
/** Constant DEFAULT_LEGACY_PWM_CHIP=0 */
/** In Pi Models Previous to RP1 the chip is number 0 */
public static int DEFAULT_LEGACY_PWM_CHIP = 0;
/** Constant DEFAULT_RP1_PWM_CHIP=2 */
/** In RP1 the chip is number 2 */
public static int DEFAULT_RP1_PWM_CHIP = 2;
/** Constant DEFAULT_PWM_CHIP=2 */
/** In RP1 the chip is number 2 */
public static int DEFAULT_PWM_CHIP = DEFAULT_RP1_PWM_CHIP;
protected final String systemPath;
protected final int chip;
protected final int address;
protected final String pwmPath;
public enum Polarity{
NORMAL,
INVERSED,
UNKNOWN
}
/**
* Constructor for LinuxPwm.
*
* @param systemPath a {@link String} object.
* @param address a int.
*/
public LinuxPwm(String systemPath, int chip, int address){
this.chip = chip;
this.address = address;
this.systemPath = Paths.get(systemPath, String.format("pwmchip%d", chip)).toString();
this.pwmPath = Paths.get(this.systemPath, String.format("pwm%d", address)).toString();
}
/**
* Constructor for LinuxPwm.
*
* @param systemPath a {@link String} object.
* @param address a int.
*/
public LinuxPwm(String systemPath, int address) {
this(DEFAULT_SYSTEM_PATH, DEFAULT_PWM_CHIP, address);
}
/**
* Constructor for LinuxPwm.
*
* @param address a int.
*/
public LinuxPwm(int address){
this(DEFAULT_SYSTEM_PATH, address);
}
/**
* channels.
* The number of PWM channels this chip supports (read-only).
*
* @return The number of PWM channels this chip supports
* @throws IOException if any.
*/
public int channels() throws IOException {
return getChannels();
}
/**
* getChannels.
* The number of PWM channels this chip supports (read-only).
*
* @return The number of PWM channels this chip supports
* @throws IOException if any.
*/
public int getChannels() throws IOException {
var path = Paths.get(systemPath,"npwm");
return Integer.parseInt(Files.readString(path).trim());
}
/**
* Export GPIO pin by SoC address
*
* @throws IOException if any.
*/
public void export() throws IOException {
var path = Paths.get(systemPath, "export");
Files.writeString(path, Integer.toString(address));
}
/**
* unexport.
*
* @throws 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 IOException if any.
*/
public boolean isExported() throws IOException {
return Files.exists(Paths.get(pwmPath));
}
/**
* polarity.
*
* @param polarity a {@link LinuxPwm.Polarity} object.
* @throws IOException if any.
*/
public void polarity(Polarity polarity) throws IOException {
setPolarity(polarity);
}
/**
* setPolarity.
*
* @param polarity a {@link LinuxPwm.Polarity} object.
* @throws IOException if any.
*/
public void setPolarity(Polarity polarity) throws IOException {
var path = Paths.get(pwmPath, "polarity");
Files.writeString(path, polarity.name().toLowerCase());
}
/**
* polarity.
*
* @return a {@link LinuxPwm.Polarity} object.
* @throws IOException if any.
*/
public Polarity polarity() throws IOException {
return getPolarity();
}
/**
* getPolarity.
*
* @return a {@link LinuxPwm.Polarity} object.
* @throws IOException if any.
*/
public Polarity getPolarity() throws IOException {
var path = Paths.get(pwmPath, "polarity");
switch(Files.readString(path).trim().toLowerCase()){
case "inversed": return Polarity.INVERSED;
case "normal": return Polarity.NORMAL;
default: return Polarity.UNKNOWN;
}
}
/**
* enable.
* Enable the PWM signal (read/write).
*
* @throws IOException if any.
*/
public void enable() throws IOException {
setEnabled(true);
}
/**
* disable.
* Disable the PWM signal (read/write).
*
* @throws IOException if any.
*/
public void disable() throws IOException {
setEnabled(false);
}
/**
* enabled.
* Enable/disable the PWM signal (read/write).
*
* @param enabled a boolean.
* @throws IOException if any.
*/
public void enabled(boolean enabled) throws IOException {
setEnabled(enabled);
}
/**
* setEnabled.
* Enable/disable the PWM signal (read/write).
*
* @param enabled a boolean.
* @throws IOException if any.
*/
public void setEnabled(boolean enabled) throws IOException {
var path = Paths.get(pwmPath,"enable");
Files.writeString(path, (enabled ? "1" : "0"));
}
/**
* enabled.
*
* @return a boolean.
* @throws IOException if any.
*/
public boolean enabled() throws IOException {
return isEnabled();
}
/**
* isEnabled.
*
* @return a boolean.
* @throws IOException if any.
*/
public boolean isEnabled() throws IOException {
var path = Paths.get(pwmPath,"enable");
return Files.readString(path).trim().equalsIgnoreCase("1");
}
/**
* period.
* The total period of the PWM signal (read/write). Value is in nanoseconds and is the sum of the active and inactive time of the PWM.
*
* @param period a long value representing nanoseconds.
* @throws IOException if any.
*/
public void period(long period) throws IOException {
setPeriod(period);
}
public void period(Number period) throws IOException {
setPeriod(period);
}
/**
* setPeriod.
*
* @param period a long value representing nanoseconds.
* @throws IOException if any.
*/
public void setPeriod(long period) throws IOException {
var path = Paths.get(pwmPath,"period");
Files.writeString(path, Long.toUnsignedString(period));
}
public void setPeriod(Number period) throws IOException {
var path = Paths.get(pwmPath,"period");
Files.writeString(path, period.toString());
}
/**
* period.
* The total period of the PWM signal (read/write). Value is in nanoseconds and is the sum of the active and inactive time of the PWM.
*
* @return the period value in nanoseconds
* @throws IOException if any.
*/
public long period() throws IOException {
return getPeriod();
}
/**
* getPeriod.
* The total period of the PWM signal (read/write). Value is in nanoseconds and is the sum of the active and inactive time of the PWM.
*
* @return the period value in nanoseconds
* @throws IOException if any.
*/
public long getPeriod() throws IOException {
var path = Paths.get(pwmPath,"period");
return Long.parseLong(Files.readString(path).trim());
}
/**
* dutyCycle.
* The active time of the PWM signal (read/write). Value is in nanoseconds and must be less than the period.
*
* @param dutyCycle a long value representing nanoseconds.
* @throws IOException if any.
*/
public void dutyCycle(long dutyCycle) throws IOException {
setDutyCycle(dutyCycle);
}
/**
* setDutyCycle.
* The active time of the PWM signal (read/write). Value is in nanoseconds and must be less than the period.
*
* @param dutyCycle a long value representing nanoseconds.
* @throws IOException if any.
*/
public void setDutyCycle(long dutyCycle) throws IOException {
var path = Paths.get(pwmPath,"duty_cycle");
Files.writeString(path, Long.toString(dutyCycle));
}
/**
* dutyCycle.
* The active time of the PWM signal (read/write). Value is in nanoseconds and must be less than the period.
*
* @return the duty cycle value in nanoseconds
* @throws IOException if any.
*/
public long dutyCycle() throws IOException {
return getDutyCycle();
}
/**
* getDutyCycle.
* The active time of the PWM signal (read/write). Value is in nanoseconds and must be less than the period.
*
* @return the duty cycle value in nanoseconds
* @throws IOException if any.
*/
public long getDutyCycle() throws IOException {
var path = Paths.get(pwmPath,"duty_cycle");
return Long.parseLong(Files.readString(path).trim());
}
/**
* Get Linux File System path for PWM
* @return Linux File System path for PWM
*/
public String systemPath(){
return getSystemPath();
}
/**
* Get Linux File System path for PWM
* @return Linux File System path for PWM
*/
public String getSystemPath(){
return this.systemPath;
}
/**
* Get Linux File System path for this PWM pin instance
* @return Linux File System path for this PWM pin instance
*/
public String pwmPath(){
return getPwmPath();
}
/**
* Get Linux File System path for this PWM pin instance
* @return Linux File System path for this PWM pin instance
*/
public String getPwmPath(){
return this.pwmPath;
}
}
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