c#单根覆盆子pi与Raspberry#获取操作无效

Question

我试图使用Raspberry#库来执行基本任务，在Raspberry#上使用GPIO引脚(on和off)。以github：https://github.com/raspberry-sharp/raspberry-sharp-io/wiki/Raspberry.IO.GeneralPurpose为例

代码：

        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();

在在线var connection = new GpioConnection(led1);上，我得到了异常：

“由于对象的当前状态，操作无效”

堆栈跟踪

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

我可以用Python切换引脚状态，所以设备没有什么问题。

Answer 1

以root用户身份执行Mono程序。一般用户无法访问/dev/mem。

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
            );
        }
    }

来自这里的解释：http://www.raspberrypi.org/forums/viewtopic.php?f=29&t=22515

要打开/dev/mem，您既需要对设备文件的常规访问权限，也需要安全功能CAP_SYS_RAWIO，或者是根用户。这是无法解决的，因为对内存的完全访问允许的不仅仅是GPIO。它对安全有着巨大的影响。