第二次运行时清除代码 [英] Clear code the second time it runs

问题描述

将我用于控制覆盆子的GPIO的这部分代码用白色。

当我点击开始按钮然后停止按钮时，继电器正常工作。当我第二次这样做时，我得到一个错误。我做错了什么...

Whit this part of my code I use to control the GPIO of a raspberry.
When I click on the start button and then the stop button the relay is working properly. When I do this for the second time i get an error. What am I doing wrong...

{
   private const int relay1 = 4;
   private const int relay2 = 25;
   private const int relay3 = 22;
   private const int relay4 = 5;
   private GpioPin pin;
   private GpioPinValue pinValue;

   public MainPage()
   {
      //Scherm laden
      InitializeComponent();
   }

   //Relay1 START
   private void StartR1_Click(object sender, RoutedEventArgs e)
   {
      var gpio = GpioController.GetDefault();
      pin = gpio.OpenPin(relay1);
      pinValue = GpioPinValue.High;
      pin.Write(pinValue);
      pin.SetDriveMode(GpioPinDriveMode.Output);

      //Button Control Aan/Uit
      StartR1.IsEnabled = false;
      StopR1.IsEnabled = true;

   }

   //Relay1 STOP
   private void StopR1_Click(object sender, RoutedEventArgs e)
   {
      var gpio = GpioController.GetDefault();
      pinValue = GpioPinValue.Low;
      pin.Write(pinValue);
      pin.SetDriveMode(GpioPinDriveMode.Input);

      //Button Control Aan/Uit
      StartR1.IsEnabled = true;
      StopR1.IsEnabled = false;

   }

推荐答案

狂猜：第二次，调用 openPin 方法失败，因为该引脚已在独占模式下打开（请参阅文档 [ ^ ]）。

如果是那么你应该只进行一次这样的调用（可能是你的应用程序启动时）。

Wild guess: the second time, the call to the openPin method fails because the pin is already open in exclusive mode (see the documentation[^]).
If that is the case then you should make such call just one time (possibly at your application startup).

看这里： https://ms-iot.github.io/content/en-US/win10/samples/PinMappingsRPi2.htm [
打开的针脚是处置 [ ^ ]（用using子句包装）。

你不能简单地重新打开它。正确使用IDisposable模式。

Look here: https://ms-iot.github.io/content/en-US/win10/samples/PinMappingsRPi2.htm[^]

The pin opened is disposed[^] (wrapped in using clause).
You can't simply reopen it. Use the IDisposable pattern properly.

CPallini和Zoltan的解决方案是正确的。更具体地说，您需要执行以下操作：

CPallini's and Zoltan's solutions are correct. More specifically, you need to do the following:

var gpio = GpioController.GetDefault();
if (pin == null) // add this line.
    pin = gpio.OpenPin(relay1);

祝你好运！

Good luck!

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