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.

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_HIDn_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

int main (void) {
  usbStatus usb_status;                 // USB status
  int       status;                     // Generic status
  int       ch;                         // Character
  uint8_t   con = 0U;                   // Connection status of keyboard
 
  SystemCoreClockUpdate();              // Update system clock
 
  status = stdout_init ();              // Initialize retargeted stdout
  if (status != 0) {
    for (;;) {}                         // Handle stdout init failure
  }
 
  usb_status = USBH_Initialize (0U);    // Initialize USB Host 0
  if (usb_status != usbOK) {
    for (;;) {}                         // Handle USB Host 0 init failure
  }
 
  for (;;) {
    usb_status= USBH_HID_GetStatus(0U); // Get HID device status
    if (usb_status == usbOK) {
      if (con == 0U) {                  // If keyboard was not connected previously
        con = 1U;                       // Keyboard got connected
        printf ("Connect!\n");
      }
    } else {
      if (con == 1U) {                  // If keyboard was connected previously
        con = 0U;                       // Keyboard got disconnected
        printf ("\nDisconnect!\n");
      }
    }
    if (con != 0U) {                    // If keyboard is active
      ch = USBH_HID_GetKeyboardKey (0U);// Get pressed key
      if (ch != -1) {                   // If valid key value
        if ((ch & 0x10000) != 0) {      // Handle non-ASCII translated keys (Keypad 0 .. 9)
                                        // Bit  16:    non-ASCII bit (0 = ASCII, 1 = not ASCII)
                                        // Bits 15..8: modifiers (SHIFT, ALT, CTRL, GUI)
                                        // Bits  7..0: ASCII or HID key Usage ID if not ASCII
          ch &= 0xFF;                   // Remove non-ASCII bit and modifiers
          if ((ch>=0x59)&&(ch<=0x61)) { // Keypad 1 .. 9 key convert to
            ch = (ch - 0x59) + '1';     // ASCII  1 .. 9
          } else if (ch == 0x62) {      // Keypad 0 key convert to
            ch = '0';                   // ASCII  0
          } else {                      // If not Keypad 0 .. 9
            ch = -1;                    // invalidate the key
          }
        }
        if ((ch > 0) && (ch < 128)) {   // Output ASCII 0 .. 127 range
          putchar(ch);
          fflush(stdout);
        }
      }
    }
    osDelay(10U);
  }
}