Raspberry Pi Zero W PWM issues

[UnAfraid]

Describe the bug
I am trying to do PWM on LED with Raspberry PI Zero W, but no matter on which pin i try i always get
bcm283x-gpio (GPIO19): bcm283x-dma: no channel available

It works only on 0% and 100%

To Reproduce
Steps to reproduce the behavior:

1. Run program

package main

import (
	"log"
	"periph.io/x/periph/conn/gpio"
	"periph.io/x/periph/conn/gpio/gpioreg"
	"periph.io/x/periph/conn/physic"
	"periph.io/x/periph/host"
	"time"
)

func main() {
	_, err := host.Init()
	if err != nil {
		log.Fatalf("Couldn't initialize host: %s", err.Error())
	}

	greenGPIO := gpioreg.ByName("19")
	if err := greenGPIO.Out(gpio.Low); err != nil {
		log.Fatalf("Failed to parse green led to low: %s", err.Error())
	}
	go func() {
		i, err := gpio.ParseDuty("10%")
		if err != nil {
			log.Fatalf("Failed to parse duty cycle: %s", err.Error())
		}

		step := i / 2

		for {
			log.Printf("Raising PWM to: %v duty", i)
			if err := greenGPIO.PWM(i, 10*physic.KiloHertz); err != nil {
				log.Printf("Failed to set PWM: %s", err.Error())
			}

			i += step
			if i > gpio.DutyMax {
				break
			}

			time.Sleep(1000 * time.Millisecond)
		}
	}()
}

2. Run it.
3. See error

Expected behavior
I am expecting to dim the LED

Platform (please complete the following information):

• OS: Raspbian Stretch Lite
• Board: Raspberry Pi Zero Wireless

Additional context
I am attempting to control the dimming on LEDs of this button: https://www.aliexpress.com/item/30mm-red-bi-color-RGB-led-Metal-Push-Button-Switch-momentary-latching-waterpoof-2no2nc-pushbutton-switch/32954214211.html

[maruel]

Try using the pins which have native PWM; you can retrieve them with "PWM0" and "PWM1".

[UnAfraid]

Okay i've set the following, but i still get the same result

pwm0 := gpioreg.ByName("PWM0")
pwm1 := gpioreg.ByName("PWM1")

Raising PWM to: 10% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 15% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 20% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 25% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 30% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 35% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 40% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 45% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 50% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 55% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 60% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 65% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 70% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 75% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 80% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 85% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 90% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available
Raising PWM to: 95% duty
Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available
Failed to set PWM1: bcm283x-gpio (GPIO13): bcm283x-dma: no channel available

[NeuralSpaz]

this work on my pi zero stretch

package main

import (
	"log"
	"periph.io/x/periph/conn/gpio"
	"periph.io/x/periph/conn/gpio/gpioreg"
	"periph.io/x/periph/conn/physic"
	"periph.io/x/periph/host"
	"time"
)

func main() {
	_, err := host.Init()
	if err != nil {
		log.Fatalf("Couldn't initialize host: %s", err.Error())
	}

	pwm0 := gpioreg.ByName("PWM1")
	if err := pwm0.Out(gpio.Low); err != nil {
		log.Fatalf("Failed to parse green led to low: %s", err.Error())
	}
	//	go func() {
	i, err := gpio.ParseDuty("10%")
	if err != nil {
		log.Fatalf("Failed to parse duty cycle: %s", err.Error())
	}

	step := i / 2

	for {
		log.Printf("Raising PWM to: %v duty", i)
		if err := pwm0.PWM(i, 10*physic.KiloHertz); err != nil {
			log.Printf("Failed to set PWM: %s", err.Error())
		}

		i += step
		if i > gpio.DutyMax {
			break
		}

		time.Sleep(1000 * time.Millisecond)
	}
	//	}()
}

[UnAfraid]

After restart of my PI it worked for a while, but after restart of my application a couple of times got it into that state again
After 5 re-launches of my application it got into that Failed to set PWM0: bcm283x-gpio (GPIO12): bcm283x-dma: no channel available do i have to free up some resource maybe?

[NeuralSpaz]

I get that too on next execution.

[NeuralSpaz]

You MUST call Halt on the pin before exiting.
eg:

package main

import (
	"log"
	"periph.io/x/periph/conn/gpio"
	"periph.io/x/periph/conn/gpio/gpioreg"
	"periph.io/x/periph/conn/physic"
	"periph.io/x/periph/host"
	"time"
)

func main() {
	if _, err := host.Init(); err != nil {
		log.Println(err)
	}

	pwm0 := gpioreg.ByName("PWM1")
	defer pwm0.Halt()
	if err := pwm0.Out(gpio.Low); err != nil {
		log.Fatalf("Failed to parse green led to low: %s", err.Error())
	}

	i, err := gpio.ParseDuty("10%")
	if err != nil {
		log.Fatalf("Failed to parse duty cycle: %s", err.Error())
	}

	step := i / 2

	for {
		log.Printf("Raising PWM to: %v duty", i)
		if err := pwm0.PWM(i, 10*physic.KiloHertz); err != nil {
			log.Printf("Failed to set PWM: %s", err.Error())
		}

		i += step
		if i > gpio.DutyMax {
			break
		}

		time.Sleep(1000 * time.Millisecond)
	}
}

[NeuralSpaz]

doc is here:
https://godoc.org/periph.io/x/periph/host/bcm283x#Pin.PWM

[NeuralSpaz]

Watching the PWM out on a scope, I noticed that if there is a SIGINT (ctrl+c) that the pwm would not Halt correctly and would continue outputting the last pwm, and not release the dma?
one possible way around this is to get the handle the signal in the program and call Halt() there as well.
eg:

...
	pwm0 := gpioreg.ByName("PWM1")
	defer pwm0.Halt()
	if err := pwm0.Out(gpio.Low); err != nil {
		log.Fatalf("Failed to parse green led to low: %s", err.Error())
	}

	var halt = make(chan os.Signal)
	signal.Notify(halt, syscall.SIGTERM)
	signal.Notify(halt, syscall.SIGINT)

	go func() {
		select {
		case <-halt:
			if err := pwm0.Halt(); err != nil {
				log.Println(err)
			}
			os.Exit(1)
		}
	}()
...

[maruel]

Looks like user error, closing.

That said, the v4 API must make it very obvious so users hardly can make this error.