GpioController is not correctly identifying Raspberry Pi with Revision c03112

I would like to use Dht11 module on Raspberry PI 4 Revision 1.2 (Model C03112).

Steps to reproduce

using (Dht11 dht = new Dht11(17))
{
    var temperature = dht.Temperature;
}

Expected behavior

Accessing dht.Temperature must work without getting an exception. Used PI model supports InputPulUp pin mode.

Actual behavior

Exception occurs when accessing dht.Temperature.

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Device.Gpio.dll: 'Pin 17 does not support mode InputPullUp.'

Further analysis

In Issue 1145 there is a workaround described:

GpioDriver driver = new RaspberryPi3Driver();
GpioController controller = new GpioController(PinNumberingScheme.Logical, driver);

Unfortunately this also does not help because PI model could not be detected and RaspberryPi3Driver() cannot be initialized.

An unhandled exception of type 'System.PlatformNotSupportedException' occurred in System.Device.Gpio.dll: 'Not a supported Raspberry Pi type: Unknown'
at System.Device.Gpio.Drivers.RaspberryPi3Driver..ctor() at MyConsoleApp.Program.ReadFromDHT11()

The actual reason of that behavior is, that enum Model in System.Device.Gpio.RaspberryBoardInfo does not contain C03112 value.

Model C03112 is officially listed on Raspberry.org, model C03114 seems also not supported.

Versions used

Raspberry:

/proc/cpuinfo: Hardware: BCM2711 Revision: c03112 Serial : 10000000683cf6ea Model : Raspberry Pi 4 Model B Rev 1.2

OS: Linux 5.4.0-1022-raspi #25-Ubuntu SMP PREEMPT Thu Oct 15 14:22:53 UTC 2020

Dotnet:

.NET Core SDK (reflecting any global.json): Version: 3.1.403 Commit: 9e895200cd

Runtime Environment: OS Name: ubuntu OS Version: 20.04 OS Platform: Linux RID: ubuntu.20.04-arm Base Path: /usr/bin/dotnet/sdk/3.1.403/

Host (useful for support): Version: 3.1.9 Commit: 774fc3d6a9

.NET Core SDKs installed: 3.1.403 [/usr/bin/dotnet/sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.App 3.1.9 [/usr/bin/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.NETCore.App 3.1.9 [/usr/bin/dotnet/shared/Microsoft.NETCore.App]

Libraries:

Iot.Device.Bindings: 1.1.0-prerelease.20555.1 System.Device.Gpio: Version="1.1.0-prerelease.20555.1

[pgrawehr]

@krwq: There’s a link in the OP above. The page on RaspberryPi.org seems to be current, as it includes both the Rasppi 4B 8GB and the Raspi 400.

[Ellerbach]

I see. Seems that this line is causing the issue:https://github.com/dotnet/iot/blob/de328cacc0dd03d539d6508c6d6239383c44af1b/src/devices/Dhtxx/DhtBase.cs#L165. I’ve seen this issue on few other boards as well which doesn’t support input pull up. Best is for sure to change this to a normal Input (supported everywhere), the pull up has to be external (which is the case 99.9999% of the time with those sensors). So if you pull the code from the repo and adjust this line, it should work. The time we make a fix and push it. Would be perfect if you can tell us if that fixed the issue.