diff --git a/lib_xua/src/hid/xua_hid.h b/lib_xua/src/hid/xua_hid.h
index c3dfcc66..ab8b2e05 100644
--- a/lib_xua/src/hid/xua_hid.h
+++ b/lib_xua/src/hid/xua_hid.h
@@ -3,8 +3,31 @@
 #include "xud.h"
 #include "xud_std_requests.h"
 
+/**
+ *  \brief Calculate the next time to respond with a HID Report.
+ *
+ *  If the USB Host has previously sent a valid HID Set_Idle request with
+ *    a duration of zero or greater than the default reporting interval,
+ *    the device sends HID Reports periodically or when the value of the
+ *    payload has changed.
+ *
+ *  This function calculates the time for sending the next periodic
+ *    HID Report.
+ */
 void HidCalcNextReportTime( void );
 
+/**
+ *  \brief Capture the time of sending the current HID Report.
+ *
+ *  If the USB Host has previously sent a valid HID Set_Idle request with
+ *    a duration of zero or greater than the default reporting interval,
+ *    the device sends HID Reports periodically or when the value of the
+ *    payload has changed.
+ *
+ *  This function captures the time when the HID Report was sent so that
+ *    a subsequent call to HidCalNextReportTime() can calculate the time
+ *    to send the next periodic HID Report.
+ */
 void HidCaptureReportTime( void );
 
 XUD_Result_t HidInterfaceClassRequests(
@@ -12,4 +35,20 @@ XUD_Result_t HidInterfaceClassRequests(
   XUD_ep c_ep0_in,
   REFERENCE_PARAM( USB_SetupPacket_t, sp ));
 
+/**
+ *  \brief Indicate whether to send a HID Report based on elapsed time.
+ *
+ *  If the USB Host has previously sent a valid HID Set_Idle request with
+ *    a duration of zero or greater than the default reporting interval,
+ *    the device sends HID Reports periodically or when the value of the
+ *    payload has changed.
+ *
+ *  This function monitors the passage of time and reports to the caller
+ *    whether or not the time to send the next periodic HID Report has
+ *    elapsed.
+ *
+ *  \return   A Boolean value indicating whether or not to send the HID Report.
+ *  \retval   1 -- Do not send the HID Report
+ *  \retval   0 -- Send the HID Report
+ */
 unsigned HidIsSetIdleSilenced( void );