usbd_hid_get_report_trigger

#include <RTL.h>
#include <rl_usb.h>

BOOL usbd_hid_get_report_trigger (
  U8  rid,                    // Report ID
  U8* buf,                    // Pointer to the buffer to report data
  int len                     // Length of report data
);

The function usbd_hid_get_report_trigger asynchronously prepares data that will be returned to the USB Host upon request. This function enables USB Device to report only when an event has occurred.

For example usually USB Host sets idle time to infinity upon HID Device enumeration what means that Host expects data from device only when something has changed so function usbd_hid_get_report_trigger is used to prepare data when something has changed. If idle time is not set to infinity then usbd_hid_get_report function is called on each idle time period expiry.

The function should be used by application code on event that needs to update report data and it only is used for report type of HID_REPORT_INPUT.

Arguments:

• rid: report ID (0 - if only one report exists in system)
• buf: pointer to the buffer with report data
• len: length of report data

The function usbd_hid_get_report_trigger is part of the USB Device Function Driver layer of the RL-USB Device Software Stack.

Modify this function to the application needs.

A boolean value indicating whether the trigger function executed successfully.

usbd_hid_get_protocol, usbd_hid_get_report, usbd_hid_init, usbd_hid_set_protocol, usbd_hid_set_report

#include <rl_usb.h>

int main (void) {
  static U8 pin_ex;
         U8 pin;
         U8 buf[1];

  usbd_init ();                          // USB Device Initialization
  usbd_connect (__TRUE);                 // USB Device Connect

  while (1) {                            // Loop forever
    pin = ... (get pin state)
    if (pin ^ pin_ex) {                  // If pin state changed
      buf[0] = pin;
      usbd_hid_get_report_trigger(0, buf, 1);
      pin_ex = pin;
    }
  };
}