USB-HID多点触摸的报告描述符和报告描述符中Feature报告的处理方法

code uint8 ReportDescriptor[]=
{
  #ifdef TOUCH_SCREEN
  0x05, 0x0d, // USAGE_PAGE (Digitizers)
  0x09, 0x04, // USAGE (Touch Screen)
  0xa1, 0x01, // COLLECTION (Application)
  0x85, REPORTID_MTOUCH, // REPORT_ID (Touch)
  0x09, 0x22, // USAGE (Finger)
  //contact 1
  0xa1, 0x02, // COLLECTION (Logical)
  0x09, 0x42, // USAGE (Tip Switch)
  0x15, 0x00, // LOGICAL_MINIMUM (0)
  0x25, 0x01, // LOGICAL_MAXIMUM (1)
  0x75, 0x01, // REPORT_SIZE (1)
  0x95, 0x01, // REPORT_COUNT (1)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x09, 0x32, // USAGE (In Range)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x95, 0x06, // REPORT_COUNT (6)
  0x81, 0x03, // INPUT (Cnst,Ary,Abs)
  0x75, 0x08, // REPORT_SIZE (8)
  0x09, 0x51, // USAGE ( Contact Identifier)
  0x25, 0xFF,	//	LOGICAL_MAXIMUM (255)
  0x95, 0x01, // REPORT_COUNT (1)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x05, 0x01, // USAGE_PAGE (Generic Desk..
 0x26,(uint8)(SCRN_RESOLUTION_X&0xFF),(uint8)((SCRN_RESOLUTION_X>>8)&0xFF), LOGICAL_MAXIMUM 
  0x75, 0x10, // REPORT_SIZE (16)
  0x55, 0x00, // UNIT_EXPONENT (0)
  0x65, 0x00, // UNIT (00)
  0x09, 0x30, // USAGE (X)
  0x35, 0x00, // PHYSICAL_MINIMUM (0)
  0x46,(uint8)(SCRN_RESOLUTION_X&0xFF),(uint8)((SCRN_RESOLUTION_X>>8)&0xFF), // PHYSICAL_MAXIMUM (1920) 
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x26, (uint8)(SCRN_RESOLUTION_Y&0xFF),(uint8)((SCRN_RESOLUTION_Y>>8)&0xFF), // LOGICAL_MAXIMUM 
  0x46, (uint8)(SCRN_RESOLUTION_Y&0xFF),(uint8)((SCRN_RESOLUTION_Y>>8)&0xFF), // PHYSICAL_MAXIMUM (1080)
  0x09, 0x31, // USAGE (Y)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0xc0, // END_COLLECTION
//contact 2
  0x05, 0x0d, // USAGE_PAGE (Digitizers)
  0x09, 0x22, // USAGE (Finger)
  0xa1, 0x02, // COLLECTION (Logical)
  0x05, 0x0d, // USAGE_PAGE (Digitizers)
  0x09, 0x42, // USAGE (Tip Switch)
  0x15, 0x00, // LOGICAL_MINIMUM (0)
  0x25, 0x01, // LOGICAL_MAXIMUM (1)
  0x75, 0x01, // REPORT_SIZE (1)
  0x95, 0x01, // REPORT_COUNT (1)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x09, 0x32, // USAGE (In Range)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x95, 0x06, // REPORT_COUNT (6)
  0x81, 0x03, // INPUT (Cnst,Ary,Abs)
  0x75, 0x08, // REPORT_SIZE (8)
  0x09, 0x51, // USAGE ( Contact Identifier)
  0x25, 0xFF,	// LOGICAL_MAXIMUM (255)
  0x95, 0x01, // REPORT_COUNT (1)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x05, 0x01, // USAGE_PAGE (Generic Desk..
  0x26,(uint8)(SCRN_RESOLUTION_X&0xFF),(uint8)((SCRN_RESOLUTION_X>>8)&0xFF), // LOGICAL_MAXIMUM ()
  0x75, 0x10, // REPORT_SIZE (16)
  0x55, 0x00, // UNIT_EXPONENT (0)
  0x65, 0x00, // UNIT (0)
  0x09, 0x30, // USAGE (X)
  0x35, 0x00, // PHYSICAL_MINIMUM (0)
  0x46,(uint8)(SCRN_RESOLUTION_X&0xFF),(uint8)((SCRN_RESOLUTION_X>>8)&0xFF),// 0xA0, 0x05, // PHYSICAL_MAXIMUM ()
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x26, (uint8)(SCRN_RESOLUTION_Y&0xFF),(uint8)((SCRN_RESOLUTION_Y>>8)&0xFF), // LOGICAL_MAXIMUM ()
  0x46, (uint8)(SCRN_RESOLUTION_Y&0xFF),(uint8)((SCRN_RESOLUTION_Y>>8)&0xFF), // PHYSICAL_MAXIMUM ()
  0x09, 0x31, // USAGE (Y)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0xc0, // END_COLLECTION

  0x05, 0x0d, // USAGE_PAGE (Digitizers)
  0x09, 0x54, // USAGE (Actual count)
  0x95, 0x01, // REPORT_COUNT (1)
  0x75, 0x08, // REPORT_SIZE (8)
  0x15, 0x00, // LOGICAL_MINIMUM (0)
  0x25, 0x08, // LOGICAL_MAXIMUM (8)
  0x81, 0x02, // INPUT (Data,Var,Abs)
  0x09, 0x55, // USAGE(Maximum Count)
  0xb1, 0x02, // FEATURE (Data,Var,Abs)
  0xc0, // END_COLLECTION

  0x09, 0x0E,                         // USAGE (Device Configuration)
  0xa1, 0x01,                         // COLLECTION (Application)
  0x85, REPORTID_FEATURE,             //   REPORT_ID (Configuration)              
  0x09, 0x23,                         //   USAGE (Device Settings)              
  0xa1, 0x02,                         //   COLLECTION (logical)    
  0x09, 0x52,                         //    USAGE (Device Mode)         
  0x09, 0x53,                         //    USAGE (Device Identifier)
  0x15, 0x00,                         //    LOGICAL_MINIMUM (0)      
  0x25, 0x0a,                         //    LOGICAL_MAXIMUM (10)
  0x75, 0x08,                         //    REPORT_SIZE (8)         
  0x95, 0x02,                         //    REPORT_COUNT (2)         
  0xb1, 0x02,                         //   FEATURE (Data,Var,Abs    
  0xc0,                               //   END_COLLECTION
  0xc0,                               // END_COLLECTION	
  #endif
};

在报告描述符中的最后，有一个Feature主项目，做项目时就遇到这个问题不会处理，后来查阅了协议文档，处理如下：

    USB协议定义了多种请求类型，Feature就需要在类输入请求中的GET_REPORT请求代码下返回Feature请求的内容。主机发送的8字节请求数据的值分别为：

 bmRequestType 10100001;

 bRequest      3; 协议中定义GET_REPORT的值为3

 wValue的高8位代表Report的类型，该值为3就表示Feature报告；

 wValue的低8位代表报告ID；

因此，我们可以根据以上请求的值判断当前请求是否要获取Feature报告，如果是，就可以讲所要数据（像报告描述符，配置描述符那样预先定义好的数据）写入端点0中。

注意：以上给出的报告描述符是两点触摸的描述符，是可以直接使用的，个别宏替换下就可以了。