Package com.oracle.deviceaccess.pwm

Interfaces and classes for generating PWM pulses on a digital output line.

See: Description

Interface Summary

Interface	Description
GenerationListener	The GenerationListener interface defines methods for getting notified of pulse generation completion conditions (i.e.
GenerationRoundListener	The GenerationRoundListener interface defines methods for getting notified of the completion of the generation of a sequence of pulses and that more pulses (the width thereof) to generate may be specified.
PWMChannel	The PWMChannel interface provides methods for controlling a PWM (Pulse Width Modulation) signal generator channel.

Class Summary

Class	Description
GenerationEvent	The GenerationEvent class encapsulates pulse a generation completion condition (i.e.
PWMChannelConfig	The PWMChannelConfig class encapsulates the hardware addressing information, and static and dynamic configuration parameters of a PWM channel.
PWMPermission	The PWMPermission class defines permissions for PWM channel access.

Exception Summary

Exception	Description
InvalidPulseRateException	Thrown by an instance of PWMChannel in case the requested pulse rate/frequency is higher than the maximum rate/frequency the PWM device can support.

Package com.oracle.deviceaccess.pwm Description

Interfaces and classes for generating PWM pulses on a digital output line.

In order to access and control a specific PWM channel, an application should first open and obtain an PWMChannel instance for the PWM generator's channel the application wants to access and control, using its numerical ID, name, type (interface) and/or properties:

Using its ID

 PWMChannel channel = (PWMChannel) PeripheralManager.open(8);
 

Using its name and interface

 PWMChannel channel = PeripheralManager.open("DIMMER", PWMChannel.class, null);
 

Once opened, an application can set the period of generated pulses using the PWMChannel.setPulsePeriod(int) method ; then generate pulses of a specified width or duty cycle by calling one of the PWMChannel.generate(int, int) or PWMChannel.startGeneration(int).

 channel.setPulsePeriod(1000000); // Pulse period = 1 second
 channel.generate(500000, 10); // Generate 10 pulses with a width of 0.5 second
 

When done, the application should call the PWMChannel.close() method to close PWM channel.

 channel.close();
 

The following sample code gives an example of using the PWM channel API to progressively dim the light of a LED (for example) starting from its maximum intensity (100% duty cycle) in 10 successive steps of 10 seconds each:

 class VaryingDimmer implements GenerationRoundListener {
 
     private PWMChannel channel = null;
     private int step = 10;
 
     public void pulseGenerationCompleted(GenerationEvent event) {
         if (step > 0) {
             try {
                 channel.startGeneration((channel.getPulsePeriod() / 10) * --step, 10, this);
             } catch (IOException ex) {
                 // Iggnored
             }
         }
     }
 
     public void start(int channelID) throws IOException, NonAvailablePeripheralException, PeripheralNotFoundException {
         if (channel != null) {
             throw new IllegalStateException();
         }
         channel = (PWMChannel) PeripheralManager.open(channelID);
         channel.setPulsePeriod(1000000); // period = 1 second
         channel.startGeneration((channel.getPulsePeriod() / 10) * step, 10, this);
     }
 
     public void stop() throws IOException, NonAvailablePeripheralException {
         if (channel != null) {
             channel.stopGeneration();
             channel.close();
         }
     }
 }
 

Because of performance issue, procedures handling PWM events, and especially event listeners, should be implemented to be as fast as possible.

Unless otherwise noted, passing a null argument to a constructor or method in any class or interface in this package will cause a NullPointerException to be thrown.