PulseOut constructor sometimes leaves the line high

[dmcomm]

CircuitPython version

Adafruit CircuitPython 7.0.0-alpha.4-115-g3c25d8e2a on 2021-07-18; Raspberry Pi Pico with rp2040

Code/REPL

import board
import pulseio
import pwmio
import time

while(True):
	pwm = pwmio.PWMOut(board.GP0, frequency=38000, duty_cycle=2**15)
	pulseOut = pulseio.PulseOut(pwm)
	time.sleep(5)
	pulseOut.deinit()
	pwm.deinit()
	time.sleep(1)

Behavior

Sometimes the line is high after creating the PulseOut object. I guess the same cause as #4908 . Though sounds like some of this code might be going away in #3264 .

Description

No response

Additional information

No response

[tannewt]

Fixed by #5019

[dmcomm]

@tannewt it's not fixed (I don't think the new code gets called by the constructor).

[dhalbert]

@DavePutz Should the constructor call send() with no pulses to get things in the right state?

[DavePutz]

I think the issue here is that anytime a PWMOut is created with a duty cycle it starts outputting immediately. I don't think that can be changed - there are library examples that depend on that behavior. So, the best we can do is turn off the PWM when a PulseOut is constructed, meaning there will likely be some (unwanted) output on the pin. I'll make that change and submit a new PR.

…

On Tue, Jul 20, 2021 at 10:21 AM Dan Halbert ***@***.***> wrote: @DavePutz <https://github.com/DavePutz> Should the constructor call send() with no pulses to get things in the right state? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#5016 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFNJKEQNEWU6V3BMDY6DFGLTYWIAJANCNFSM5ATQ62AQ> .

[dmcomm]

Fixed now, thanks :)

@DavePutz I agree the brief unwanted output on the pin is expected behaviour with the current API. I asked in #3264 whether it could be removed in the new API.