com.pi4j.wiringpi

Class SoftTone

java.lang.Object

com.pi4j.wiringpi.SoftTone

public class SoftTone
extends Object

WiringPi includes a software-driven sound handler capable of outputting a simple tone/square wave signal on any of the Raspberry Pi’s GPIO pins.

There are some limitations… To maintain a low CPU usage, the minimum pulse width is 100μS. That gives a maximum frequency of 1/0.0002 = 5000Hz.

Also note that while the routines run themselves at a higher and real-time priority, Linux can still affect the accuracy of the generated tone.

However, within these limitations, simple tones on a high impedance speaker or piezo sounder is possible.

NOTES: - Each pin activated in softTone mode uses approximately 0.5% of the CPU. - You need to keep your program running to maintain the sound output!

This library depends on the wiringPi native system library.
(developed by Gordon Henderson @ http://wiringpi.com/)

Author:

Robert Savage (http://www.savagehomeautomation.com)

See Also:

https://www.pi4j.com/, http://wiringpi.com/reference/software-tone-library/

Method Summary

Modifier and Type	Method and Description
static int	softToneCreate(int pin) int softToneCreate (int pin)
static void	softToneStop(int pin) void softToneStop (int pin);
static void	softToneWrite(int pin, int frequency) void softToneWrite (int pin, int frequency);

Methods inherited from class java.lang.Object

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

Method Detail

softToneCreate

public static int softToneCreate(int pin)

int softToneCreate (int pin)

This creates a software controlled tone pin. You can use any GPIO pin and the pin numbering will be that of the wiringPiSetup() function you used.

Parameters:

pin - The GPIO pin to use as a PWM pin.

Returns:

The return value is 0 for success. Anything else and you should check the global errno variable to see what went wrong.

See Also:

http://wiringpi.com/reference/software-tone-library/

softToneWrite

public static void softToneWrite(int pin,
                                 int frequency)

void softToneWrite (int pin, int frequency);

This updates the tone frequency value on the given pin. The tone will be played until you set the frequency to 0.

Parameters:

pin - The GPIO pin to use.

frequency - The frequency value set on the GPIO pin. Set of value of '0' to stop the tone.

See Also:

http://wiringpi.com/reference/software-tone-library/

softToneStop

public static void softToneStop(int pin)

void softToneStop (int pin);

This stops any tone frequency value on the given pin.

Parameters:

pin - The GPIO pin to use.

See Also:

http://wiringpi.com/reference/software-tone-library/