PWM does not work

[esemlak]

Hi,

I am trying to rewrite a working Python script in PI4J 2.0 but somehow the same pin does not send any signal.
What am I missing?!

Python:

import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(18, GPIO.OUT)
 
p = GPIO.PWM(18, 440)  # frequency=440Hz
p.start(0)
try:
    while 1:
        for dc in range(0, 101, 5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
        for dc in range(100, -1, -5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
except KeyboardInterrupt:
    pass
    p.stop()
    GPIO.cleanup()

Java:

import com.pi4j.Pi4J;
import com.pi4j.context.Context;
import com.pi4j.io.pwm.Pwm;
import com.pi4j.io.pwm.PwmConfig;
import com.pi4j.io.pwm.PwmType;

public class PwmDemo {


    static Pwm pwm;

    public static void showDemo() {
        int address = 18;
        System.out.println("tryPwm " + address);
        Context pi4j = Pi4J.newAutoContext();
        PwmConfig config = Pwm.newConfigBuilder(pi4j)
                .id("BCM" + address)
                .name("Buzzer")
                .address(address)
                .pwmType(PwmType.HARDWARE)
                .initial(0)
                .shutdown(0)
                .build();

        pwm = pi4j.create(config);

        playTone(55,1000);
        playTone(110,1000);
        playTone(220,1000);

        pwm.shutdown(pi4j);
        pi4j.shutdown();
    }

    private static void playTone(int frequency, int duration) {
        System.out.println("playTone frequency " + frequency + " duration " + duration);

        pwm.on(50, frequency);
        try {
            Thread.sleep(duration);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        pwm.off();

    }

}

[esemlak]

Apparently, the config needs a provider specified:

        PwmConfig config = Pwm.newConfigBuilder(pi4j)
                .id("BCM" + address)
                .name("Buzzer")
                .address(address)
                .pwmType(PwmType.HARDWARE)
                .initial(0)
                .shutdown(0)
                .provider("pigpio-pwm")
                .build();

The example here came without https://pi4j.com/documentation/io-examples/pwm/

[FDelporte]

@esemlak thanks for noticing and providing the solution!!! The documentation page has been adjusted.

[savageautomate]

@esemlak ,

Yes as the moment all I/O providers need to be explicitly specified. We plan on assigning default I/O providers in a future release once all the Linux File System providers are complete.

Thanks, Robert