Opening an output pin with libpgiod driver changes the pin value

Describe the bug

I want to read the value from an output pin, but by just opening an output pin it gets set to high. So reading it always returns high of course.

But using gpioget to read the pin value returns it as low, if that was what it was.

Steps to reproduce

Create GPIO controller Open pin (for one that is low) It is set to high, without an explicit write

var led1 = 19;

using var gpio = new GpioController(PinNumberingScheme.Logical, new LibGpiodDriver(2));

gpio.OpenPin(led1, PinMode.Output);
// gpio.Write(led1, PinValue.High);
gpio.ClosePin(led1);

Expected behavior

I expected to be able to open the pin without its state being affected, so I could read the state afterwards.

Actual behavior

Opening the pin changes state.

Versions used

Debian 10 (arm64) System.Device.Gpio package: 1.3.0 .NET Core: 3.1

Dockerfile

FROM mcr.microsoft.com/dotnet/sdk:3.1 as build

WORKDIR /src
COPY GpioApp.csproj ./
RUN dotnet restore GpioApp.csproj

COPY Program.cs ./
RUN dotnet build GpioApp.csproj -c Release -o /app

FROM mcr.microsoft.com/dotnet/runtime:3.1-alpine-arm64v8 as final

RUN apk update && apk add libgpiod-dev

WORKDIR /app
COPY --from=build /app .
ENTRYPOINT ["dotnet", "GpioApp.dll"]

docker run --privileged --rm dotnet-gpio:3.1

[krwq]

@raffaeler we now have a new nightly package you can try out. The nightly should work now (minus flaky tests which can be retried)

[krwq]

@raffaeler theoretically: https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json (note dotnet6 not dotnet5)

has the latest but seems to me the last package is from June 4 which seems something is wrong with the publishing even though I’m seeing successful builds in the pipeline. I will ask our engineering team if they know what’s wrong