com.pi4j.wiringpi.GpioUtil Maven / Gradle / Ivy
package com.pi4j.wiringpi;
/*
* #%L
* **********************************************************************
ORGANIZATION : Pi4J
PROJECT : Pi4J :: Java Library (Core)
FILENAME : GpioUtil.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 - 2018 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.util.NativeLibraryLoader;
/**
* This utility class is provided to export, unexport, and manipulate pin direction.
*
*
* Before using the Pi4J library, you need to ensure that the Java VM in configured with access to
* the following system libraries:
*
* - pi4j
* - wiringPi
*
* This library depends on the wiringPi native system library. (developed by
* Gordon Henderson @ http://wiringpi.com/)
*
*
*
* @see http://www.pi4j.com/
* @see http://wiringpi.com/
* @author Robert Savage (http://www.savagehomeautomation.com)
*/
public class GpioUtil {
// private constructor
private GpioUtil() {
// forbid object construction
}
static {
// Load the platform library
NativeLibraryLoader.load("libpi4j.so");
}
/**
* GPIO PIN DIRECTION
*
* GPIO pin constant for IN direction for reading pin states
*
*
* @see #export(int,int)
* @see #setDirection(int,int)
* @see #getDirection(int)
*/
public static final int DIRECTION_IN = 0;
/**
* GPIO PIN DIRECTION
*
* GPIO pin constant for OUT direction for writing digital pin states (0/1).
*
*
* @see #export(int,int)
* @see #setDirection(int,int)
* @see #getDirection(int)
*/
public static final int DIRECTION_OUT = 1;
/**
* GPIO PIN DIRECTION
*
* GPIO pin constant for OUT direction with an initial default HIGH value for writing digital pin states (0/1).
*
*
* @see #export(int,int)
* @see #setDirection(int,int)
* @see #getDirection(int)
*/
public static final int DIRECTION_HIGH = 2;
/**
* GPIO PIN DIRECTION
*
* GPIO pin constant for OUT direction with an initial default LOW value for writing digital pin states (0/1).
*
*
* @see #export(int,int)
* @see #setDirection(int,int)
* @see #getDirection(int)
*/
public static final int DIRECTION_LOW= 3;
/**
* GPIO PIN EDGE DETECTION
*
* This constant is provided as an edge detection mode for use with the 'edge' method. This
* constants instructs the edge detection to be disabled.
*
*
* @see #setEdgeDetection(int,int)
*/
public static final int EDGE_NONE = 0;
/**
* GPIO PIN EDGE DETECTION
*
* This constant is provided as an edge detection mode for use with the 'edge' method. This
* constants instructs the edge detection to only look for rising and falling pins states; pins
* changing from LOW to HIGH or HIGH to LOW.
*
*
* @see #setEdgeDetection(int,int)
*/
public static final int EDGE_BOTH = 1;
/**
* GPIO PIN EDGE DETECTION
*
* This constant is provided as an edge detection mode for use with the 'edge' method. This
* constants instructs the edge detection to only look for rising pins states; pins changing
* from LOW to HIGH.
*
*
* @see #setEdgeDetection(int,int)
*/
public static final int EDGE_RISING = 2;
/**
* GPIO PIN EDGE DETECTION
*
* This constant is provided as an edge detection mode for use with the 'edge' method. This
* constants instructs the edge detection to only look for falling pins states; pins changing
* from HIGH to LOW.
*
*
* @see #setEdgeDetection(int,int)
*/
public static final int EDGE_FALLING = 3;
/**
*
* This method will export the selected GPIO pin.
*
*
* This method required root permissions access.
*
*
* @see #DIRECTION_IN
* @see #DIRECTION_OUT
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @param direction pin direction
*/
public static native void export(int pin, int direction) throws RuntimeException;
/**
* This method will unexport the selected GPIO pin.
* This method required root permissions access.
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
*/
public static native void unexport(int pin) throws RuntimeException;
/**
* This method determines if the requested GPIO pin is already exported.
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @return A return value of '0' represents that the pin is not exported. A return value
* of '1' represents that the pin is exported.
*/
public static native boolean isExported(int pin) throws RuntimeException;
/**
* This method will set the selected GPIO pin's edge detection. Edge detection instructs when
* the hardware GPIO changes raise interrupts on the system.
*
* NOTE: Calling this method will automatically export the pin and set the pin direction to
* INPUT. This method required root permissions access.
*
*
* @see #EDGE_NONE
* @see #EDGE_BOTH
* @see #EDGE_RISING
* @see #EDGE_FALLING
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @param edge The edge condition to detect: none, rising, falling, or both. The following
* constants are provided for use with this parameter:
*
* - EDGE_NONE
* - EDGE_BOTH
* - EDGE_RISING
* - EDGE_FALLING
*
* @return A return value of '0' represents success. Errors are returned as negative numbers.
*/
public static native boolean setEdgeDetection(int pin, int edge) throws RuntimeException;
/**
* This method will get the selected GPIO pin's edge detection setting. Edge detection instructs
* when the hardware GPIO changes raise interrupts on the system.
*
*
* @see #EDGE_NONE
* @see #EDGE_BOTH
* @see #EDGE_RISING
* @see #EDGE_FALLING
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @return The edge condition detected on the selected pin: none, rising, falling, or both.
* The following constants are provided for use with this parameter:
*
* - EDGE_NONE
* - EDGE_BOTH
* - EDGE_RISING
* - EDGE_FALLING
*
*/
public static native int getEdgeDetection(int pin) throws RuntimeException;
/**
* This method will set the selected GPIO pin's export direction.
*
* @see #DIRECTION_IN
* @see #DIRECTION_OUT
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @param direction
* The export direction to apply: IN, OUT. The following constants are provided
* for use with this parameter:
*
* - DIRECTION_IN
* - DIRECTION_OUT
*
* @return A return value of '0' represents success. Errors are returned as negative numbers.
*/
public static native boolean setDirection(int pin, int direction) throws RuntimeException;
/**
*
* This method will get the selected GPIO pin's export direction.
*
*
* @see #DIRECTION_IN
* @see #DIRECTION_OUT
*
* @param pin GPIO pin number (not header pin number; not wiringPi pin number)
* @return The GPIO pin's configured export direction is returned: IN (0), OUT (1). The
* following constants are provided for use with this parameter:
*
* - DIRECTION_IN
* - DIRECTION_OUT
*
*/
public static native int getDirection(int pin) throws RuntimeException;
/**
*
* This method will return a value of '1' if the pin is supported
*
*
* @param pin pin number
* @return '1' is the pin is supported, else '0'
*/
public static native int isPinSupported(int pin) throws RuntimeException;
/**
*
* This method will return a value of '1' if Privileged access is required.
* This method will return a value of '0' if Privileged access is NOT required.
* Privileged access is required if any of the the following conditions are not met:
* - You are running with Linux kernel version 4.1.7 or greater
* - The Device Tree is enabled
* - The 'bcm2835_gpiomem' kernel module loaded.
* - Udev rules are configured to permit write access to '/sys/class/gpio/**'
*
*
*
* @return 'true' if privileged access is required; else returns 'false'.
*/
public static native boolean isPrivilegedAccessRequired() throws RuntimeException;
/**
*
* This method is used to enable non-privileged access to the GPIO pins on
* to system. This method will throw a runtime exception if privileged access
* is required. You can test for required access using the 'isPrivilegedAccessRequired()'
* method.
*
* Please note when non-privileged access is enabled, you will not be able to
* use any hardware PWM or CLOCK functions.
*
*/
public static native void enableNonPrivilegedAccess() throws RuntimeException;
}