com.raspoid

Class PWMComponent

java.lang.Object

com.raspoid.PWMComponent

All Implemented Interfaces:

Component

Direct Known Subclasses:

IRTransmitter, LEDPWM, PassiveBuzzer, ServoMotor

public class PWMComponent
extends java.lang.Object
implements Component

This class is used as an abstraction for each component using a PWM signal.

To generate PWM signal, you can choose to use either:

• a PWM pin from the Raspberry Pi (only two PWM pins allowing real PWM signals on recent Raspberry Pi).
• a PCA9685 (16 output channels per module, but a smaller range of available PWM frequencies).

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_RPI_PWM_CLOCK_FREQUENCY Default Raspberry Pi PWM clock frequency: 19.2MHz.
static int	PCA9685_PULSE_TICKS With the PCA9685, a pulse is composed of 4096 ticks (12bits value).
protected int	pinNumber The WiringPi pin number corresponding to the PWMPin pin.

Constructor Summary

Constructors

Constructor and Description
PWMComponent(PCA9685 pca9685, PCA9685.PCA9685Channel channel, int rangeGenerator) Constructor for a PWM component, using a PCA9685 module to generate PWM signals.
PWMComponent(PWMPin pin, int rangeGenerator) Constructor for a PWM component, using a RPi hardware PWM pin to generate PWM signals.

Method Summary

Modifier and Type	Method and Description
java.lang.String	getType() Get the String representation of the type of the component.
void	setPWM(int off) Sets for each full pulse of the PWM signal, the tick where the signal turns off (low).
void	setPWM(int off, long millis) Uses the setPWM(int) method to set the PWM signal with the off parameter, for a duration of millis milliseconds, and then stops the signal.
void	setPWMFreq(double frequency) Sets the PWM frequency, which determines how many full pulses per second are generated.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_RPI_PWM_CLOCK_FREQUENCY

public static final int DEFAULT_RPI_PWM_CLOCK_FREQUENCY

Default Raspberry Pi PWM clock frequency: 19.2MHz.

See Also:

Constant Field Values

pinNumber

protected int pinNumber

The WiringPi pin number corresponding to the PWMPin pin.

This is used for performance reasons with components requiring microseconds delays.

See Also:

pin

PCA9685_PULSE_TICKS

public static final int PCA9685_PULSE_TICKS

With the PCA9685, a pulse is composed of 4096 ticks (12bits value). The recommended value for the range generator is then 4096. You can use another value, but we will round your range generator to the 0..4096 range.

See Also:

Constant Field Values

Constructor Detail

PWMComponent

public PWMComponent(PCA9685 pca9685,
                    PCA9685.PCA9685Channel channel,
                    int rangeGenerator)

Constructor for a PWM component, using a PCA9685 module to generate PWM signals.

Advantage: 16 channels on each PCA9685.

Disadvantage: target frequency must be an integer values, only between 40 and 1000Hz.

Parameters:

pca9685 - the pca9685 module used to generate PWM signals.

channel - the target channel on the pca9685 to generate the PWM signals.

rangeGenerator - the value used to define the range of values that can be used to define a signal. The tick when the signal turn off for each pulse must then be between 0 and rangeGenerator. ! Attention ! when using the PCA9685, the maximum rangeGenerator is 4096 (maximum 12-bits value). Must be >= 1.

PWMComponent

public PWMComponent(PWMPin pin,
                    int rangeGenerator)

Constructor for a PWM component, using a RPi hardware PWM pin to generate PWM signals.

Advantage: wide range of PWM frequencies, with continuous values.

Disadvantage: only 2 hardware PWM pins on recent RPi.

Parameters:

pin - the PWMPin used to generate PWM signal.

rangeGenerator - the value used to define the range of values that can be used to define a signal. The tick when the signal turn off for each pulse must then be between 0 and rangeGenerator. Must be >= 1.

See Also:

PWMPin

Method Detail

setPWMFreq

public void setPWMFreq(double frequency)

Sets the PWM frequency, which determines how many full pulses per second are generated.

Depending on the selected mode (Raspberry Pi PWM pin or PCA9685), the maximum available frequency is different.

Parameters:

frequency - the new PWM frequency.

setPWM

public void setPWM(int off)

Sets for each full pulse of the PWM signal, the tick where the signal turns off (low).

The rangeGenerator is used to define the range of values that the off tick can take. As an example, a rangeGenerator of 20000 and an off value of 5000 means that each PWM full pulse is composed of 25% high signal, followed by 75% of low signal.

! Attention ! when using the PCA9685, the maximum rangeGenerator is 4096 (maximum 12-bits value).

If you use a higher value for the off than for the rangeGenerator, we will set the off value to the rangeGenerator value.

Note that an off value of zero will stop the PWM signal.

Parameters:

off - the tick where the signal turns off (low). 0 to stop the PWM signal.

See Also:

setPWM(int, long)

setPWM

public void setPWM(int off,
                   long millis)

Uses the setPWM(int) method to set the PWM signal with the off parameter, for a duration of millis milliseconds, and then stops the signal.

Parameters:

off - the tick where the signal turns off (low).

millis - the duration of the PWM signal, in milliseconds.

See Also:

setPWM(int)

getType

public java.lang.String getType()

Description copied from interface: Component

Get the String representation of the type of the component.

Specified by:

getType in interface Component

Returns:

the String representation of the type of the component.