El Bruno

Buenas,

after the post where I mentioned How to identify a connected to a computer USB gadget information , today to see how to work with it from a C application #.

From the information in the device

First thing we will do will be to define an array of 6 elements bytes to send information to the led (line 1).

Then we define a pair of constants to identify the gadget (lines 7 and 8) and creating a type USBInterface class (see the previous post), we connect to our device.

   1: private readonly byte[] _cmdData = new byte[] { 0, 0, 0, 0, 0, 0 };

   2: private readonly USBInterface _device;

   3: private readonly bool _connected; 

   4:  

   5: public LightController()

   6: {

   7:     const string vendorId = "vid_1294"; 

   8:     const string productId = "pid_1320"; 

   9:     _device = new USBInterface(vendorId, productId);

  10:  

  11:     if (_connected)

  12:     {

  13:         return;

  14:     }

  15:     _device.enableUsbBufferEvent(UsbDeviceEventCacher);

  16:     _connected = true;

  17: }

The following will create a function to turn on or turn off the device Led. On stage is very simple, we change the 2nd element of the array from 0 to 1, and we send with the functionwriteDataSimple() .

   1: public void TurnLight(bool lightOn)

   2: {

   3:     _cmdData[1] = 0;

   4:     if (lightOn)

   5:     {

   6:         _cmdData[1] = 1;

   7:     }

   8:     _device.UsbDevice.writeDataSimple(_cmdData);

   9: }

To turn off do the same, but with the 2nd component equal to 0.

The complete code for the class would look like:

   1: using System;

   2: using System.Diagnostics;

   3: using System.Linq;

   4: using USBHIDDRIVER;

   5:  

   6: namespace ElBruno.LightNotifier

   7: {

   8:     public class LightController

   9:     {

  10:         private readonly byte[] _cmdData = new byte[] { 0, 0, 0, 0, 0, 0 };

  11:         private readonly USBInterface _device;

  12:         private readonly bool _connected; 

  13:  

  14:         public LightController()

  15:         {

  16:             const string vendorId = "vid_1294"; 

  17:             const string productId = "pid_1320"; 

  18:             _device = new USBInterface(vendorId, productId);

  19:  

  20:             if (_connected)

  21:             {

  22:                 return;

  23:             }

  24:             _device.enableUsbBufferEvent(UsbDeviceEventCacher);

  25:             _connected = true;

  26:         }

  27:  

  28:  

  29:         public void TurnLight(bool lightOn)

  30:         {

  31:             _cmdData[1] = 0;

  32:             if (lightOn)

  33:             {

  34:                 _cmdData[1] = 1;

  35:             }

  36:             _device.UsbDevice.writeDataSimple(_cmdData);

  37:         }

  38:  

  39:         private void UsbDeviceEventCacher(object sender, EventArgs e)

  40:         {

  41:             if (USBInterface.usbBuffer.Count <= 0) return;

  42:             const int counter = 0;

  43:             while (USBInterface.usbBuffer[counter] == null)

  44:             {

  45:                 lock (USBInterface.usbBuffer.SyncRoot)

  46:                 {

  47:                     USBInterface.usbBuffer.RemoveAt(0);

  48:                 }

  49:             }

  50:             var currentRecord = (byte[])USBInterface.usbBuffer[0];

  51:             lock (USBInterface.usbBuffer.SyncRoot)

  52:             {

  53:                 USBInterface.usbBuffer.RemoveAt(0);

  54:             }

  55:             if (currentRecord == null) return;

  56:             var msg = currentRecord.Aggregate("current record:", (current, t) => current + t);

  57:             msg += "\r\n";

  58:             Trace.WriteLine(msg);

  59:         }

  60:     }

  61: }

And ready! We have a class that allows you to turn on and off the LEG of our USB gadget in 60 lines.

Tomorrow the source code and the complete example.

Saludos @ La Finca

El Bruno