# RTC_SetAlarmStatusAsync

## C Specification

  `#include <nitro/rtc.h>`

      RTCResult RTC_SetAlarmStatusAsync(
      RTCAlarmChan	        chan,
      const RTCAlarmStatus*	status,
      RTCCallback		callback,
      void*			arg );

## Arguments

`chan` | Uses `RTCAlarmChan` to specify the alarm channel.
`status` | Pointer to `RTCAlarmStatus` containing status to set.
`callback` | Pointer to the callback function. This callback is called from within the interrupt handler.
`arg` | Argument to pass to the callback function.

## Return Values

If the request succeeds, it returns 0. If the request fails, it returns some numeric value other than 0.

## Description

This function asynchronously writes alarm permission status for the real time clock. It sends a request to ARM7 to allow alarm permissions and returns the process result without waiting for a response from the processor. To get the result from the processor, you must use the `result` argument. If this function fails, no operation is performed and no user callback function is called.

## Caution

In write alarm state, do not set to any state other than enable or prohibit. Values are written to the variable specified by the `status` argument asynchronously. Do not use this variable for anything else until a user callback function confirms the completion of this operation.

## See Also

`RTC_SetAlarmStatus, RTC_GetAlarmStatus, RTC_GetAlarmStatusAsync, RTCResult, RTCAlarmChan, RTCAlarmStatus, RTCCallback`

## Revision History

06/27/2005 Added statement about callback being called from the interrupt handler.
03/08/2005 Standardized the use of the term 'interrupt' in Japanese.
05/18/2004 Initial version