c# mono raspberry pi GPIO with Raspberry# getting Operation is not valid

Question

I'm trying to use Raspberry# library to perform basic task whith GPIO pin on Raspberry PI (on and off). As per example on github: https://github.com/raspberry-sharp/raspberry-sharp-io/wiki/Raspberry.IO.GeneralPurpose

Code:

        var led1 = ConnectorPin.P1Pin11.Output();
        var connection = new GpioConnection(led1);
        for (var i = 0; i < 100; i++)
        {
            connection.Toggle(led1);
            System.Threading.Thread.Sleep(250);
        }
        connection.Close();

on line var connection = new GpioConnection(led1); I get exception:

"Operation is not valid due to the current state of the object"

Stack trace

Unhandled Exception:
System.InvalidOperationException: Operation is not valid due to the current state of the object
at Raspberry.IO.GeneralPurpose.GpioConnectionDriver..ctor () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnectionSettings.get_DefaultDriver () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnectionSettings..ctor () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnection..ctor (Raspberry.IO.GeneralPurpose.GpioConnectionSettings settings, IEnumerable`1 pins) [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnection..ctor (Raspberry.IO.GeneralPurpose.PinConfiguration[] pins) [0x00000] in <filename unknown>:0
at Hello.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0
[ERROR] FATAL UNHANDLED EXCEPTION: System.InvalidOperationException: Operation is not valid due to the current state of the object
at Raspberry.IO.GeneralPurpose.GpioConnectionDriver..ctor () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnectionSettings.get_DefaultDriver () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnectionSettings..ctor () [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnection..ctor (Raspberry.IO.GeneralPurpose.GpioConnectionSettings settings, IEnumerable`1 pins) [0x00000] in <filename unknown>:0
at Raspberry.IO.GeneralPurpose.GpioConnection..ctor (Raspberry.IO.GeneralPurpose.PinConfiguration[] pins) [0x00000] in <filename unknown>:0
at Hello.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0

I am able to switch pin state with Python so nothing is wrong with device.

Answer 1

Execute your Mono program as root. /dev/mem is not accessible to normal users.

public GpioConnectionDriver() {

        using (var memoryFile = UnixFile.Open("/dev/mem", UnixFileMode.ReadWrite | UnixFileMode.Synchronized)) {
            gpioAddress = MemoryMap.Create(
                IntPtr.Zero, 
                Interop.BCM2835_BLOCK_SIZE,
                MemoryProtection.ReadWrite,
                MemoryFlags.Shared, 
                memoryFile.Descriptor,
                Interop.BCM2835_GPIO_BASE
            );
        }
    }

Explanation from here: http://www.raspberrypi.org/forums/viewtopic.php?f=29&t=22515

To open /dev/mem you need both regular access permissions on the device file and the security capability CAP_SYS_RAWIO, or to be root. There is no getting around this, because full access to memory allows a lot more than just GPIO. It has huge security implications.

Answer 2

you can use Iot.Device.Bindings package it's better

https://docs.microsoft.com/fr-fr/dotnet/iot/tutorials/blink-led