HID: Human Interface Device Class

USB Host functions to support Human Interface Device (HID) USB Devices. More...

Content
	User API
	User API reference of the Human Interface Device Class.
	Configuration
	Configuration of the USB Host HID Class in µVision.

Description

USB Host functions to support Human Interface Device (HID) USB Devices.

The HID class in the USB Component is used for attaching input devices to your system.

Refer to:

• HID: Human Interface Device Class for an overview of the HID class.
• USB Host Keyboard for an example project that uses a HID-compliant keyboard as an input.

Software Structure
The application starts the USB Host by calling USBH_Initialize. The USB Host Core will wait until an USB HID device is attached to the system. As soon as this happens it will enumerate the device and it will be ready to be used by the application. The handling of the HID class events is implemented in USBH_HID_Thread.

The transmit functions USBH_HID_Read and USBH_HID_Write will be called by the user thread directly to communicate with the HID device.

Implementation

To create an USB Host with support for the HID class:

• Select USB:Host:HID in the RTE Component Selection.
• Configure the number of USB HID devices connected in the file USBH_Config_HID.h.

Code Example

/*------------------------------------------------------------------------------
          USB Host Thread
 *----------------------------------------------------------------------------*/
void USBH_Thread (void const *arg) {
  char con    =  0;                          /* Connection status of keyboard */
  char con_ex =  40;                         /* Previous connection status    
                                                + initial time in 100 ms   
                                                intervals for initial display */
  char out    =  1;                          /* Output to keyboard LEDs       */

  USBH_Initialize (0);                       /* Initialize USB Host 0         */
  USBH_Initialize (1);                       /* Initialize USB Host 1         */

  while (1) {
    con = USBH_HID_GetDeviceStatus(0) == usbOK;  /* Get kbd connection status */
    if ((con ^ con_ex) & 1) {                /* If connection status changed  */
      if (con) {
        USBH_HID_Write (0,(uint8_t *)&out,1);/* Turn on NUM LED               */
        printf ("\nKeyboard connected\n");
      } else {
        printf ("\nKeyboard disconnected ...\n");
      }
      con_ex = con;
    } else if (con_ex > 1) {                 /* If initial time active        */
      con_ex -= 2;                           /* Decrement initial time        */
      if ((con_ex <= 1) && (!con)) {         /* If initial time expired       */
        printf ("\nNo keyboard connected ... \n");
        con_ex = con;
      } else {
        osDelay(200);
      }
    }
    osDelay(100);
  }
}
osThreadDef(USBH_Thread, osPriorityNormal, 1, NULL);