Package com.pi4j.wiringpi

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

    • 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/