ch.eitchnet.beaglebone

Class GpioBridgeImpl

java.lang.Object

ch.eitchnet.beaglebone.GpioBridgeImpl

All Implemented Interfaces:

GpioBridge

public class GpioBridgeImpl
extends Object
implements GpioBridge

Main object to give access to GPIO ports on a Linux kernel

The GpioBridge is a singleton. Features include retrieving Pins, writing and reading values, as well as registering observers for changes to input pins

Gpio objects are cached and their Signal is set by the GpioBridge accordingly

Author:

Robert von Burg <eitch@eitchnet.ch>

Method Summary

Modifier and Type	Method and Description
Gpio	getGpio(Pin pin, Direction direction) Returns the Gpio for the given Direction.
static GpioBridge	getInstance()
Signal	readValue(Gpio gpio) Public API method to read the current Signal on the given Gpio's pin.
void	register(Gpio gpio, GpioSignalListener listener) Registers the given GpioSignalListener for changes to Signals on the given Gpio
void	start() Starts the GpioBridge's signal observing Thread.
void	stop() Stops observing any pins and stops the Thread
boolean	unregister(GpioBridgeTest gpio, GpioSignalListener listener) Unregisters a GpioSignalListener from changes to the given Gpio
void	writeValue(Gpio gpio, Signal signal) Public API method to write the given Signal on the given Gpio's pin.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static GpioBridge getInstance()

Returns:

the instance of the GpioBridge

writeValue

public void writeValue(Gpio gpio,
                       Signal signal)
                throws GpioException

Public API method to write the given Signal on the given Gpio's pin.

Specified by:

writeValue in interface GpioBridge

Parameters:

gpio - the Gpio to which the Signal should be written

signal - the Signal to write to the given Gpio

Throws:

GpioException - if the direction of the Gpio is not Direction.OUT, or if something goes wrong while writing to the file

readValue

public Signal readValue(Gpio gpio)
                 throws GpioException

Public API method to read the current Signal on the given Gpio's pin.

Specified by:

readValue in interface GpioBridge

Parameters:

gpio - the Gpio for which the Signal should be read

Returns:

The Gpio's current signal

Throws:

GpioException - if the direction of the Gpio is not Direction.IN, or if something goes wrong while reading from the file

start

public void start()

Starts the GpioBridge's signal observing Thread. If no observers are registered with the register(Gpio, GpioSignalListener)-method, then this method needs not to be called.

Specified by:

start in interface GpioBridge

stop

public void stop()

Stops observing any pins and stops the Thread

Specified by:

stop in interface GpioBridge

getGpio

public Gpio getGpio(Pin pin,
                    Direction direction)
             throws GpioException

Returns the Gpio for the given Direction.

Note: This method can not be called multiple times with different Directions. The GpioBridge does not handle pins that are simultaneously input and output as this is not supported by the Linux kernel.

Specified by:

getGpio in interface GpioBridge

Parameters:

pin - The Pin for which the Gpio in the given Direction is to be returned

direction - the Direction for which this Gpio is to be returned

Returns:

The Gpio with the configured Direction

Throws:

GpioException - If the given Direction does not match the kernel's configured direction, or if the file permissions are not set so that the Java process can access the file (read access for input pin, write access for output pin.

register

public void register(Gpio gpio,
                     GpioSignalListener listener)
              throws GpioException

Registers the given GpioSignalListener for changes to Signals on the given Gpio

Specified by:

register in interface GpioBridge

Parameters:

gpio - the Gpio being observed

listener - the GpioSignalListener to be notified on changes on the Gpio's Signal

Throws:

GpioException - if the Direction of the Gpio is not Direction.IN

unregister

public boolean unregister(GpioBridgeTest gpio,
                          GpioSignalListener listener)

Unregisters a GpioSignalListener from changes to the given Gpio

Specified by:

unregister in interface GpioBridge

Parameters:

gpio - the Gpio for which the listener is to be removed

listener - the GpioSignalListener to be removed from changes to the given Gpio

Returns:

true if the listener was unregistered, false if not