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 then when an event has occurred.

For example, USB Host sets the idle time to infinity upon HID Device enumeration. This means, the Host expects data from a device only when something has changed. The function usbd_hid_get_report_trigger is used to prepare the changed data. If idle time is not set to infinity, then the usbd_hid_get_report function is called whenever the idle time period expires.

Use the function only for reports of type HID_REPORT_INPUT and for events that needs to update report data.

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

Modify this function to the application needs.

• __TRUE = executed successfully
• __FALSE (0) = failure

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;
    }
  };
}