# MIC_StartAutoSamplingAsync

## C Specification

  `#include <nitro/spi.h>`

      MICResult MIC_StartAutoSamplingAsync(
                  const MICAutoParam*    param,
                  MICCallback            callback,
                  void*                  arg );

## Arguments

param | Specifies a pointer to the `MICAutoParam` type auto-sampling structure.
callback | Specifies the pointer to the callback function. This callback is called from within the interrupt handler.
arg | Specifies the argument passed to the callback function.

## Return Values

Returns the enumerated-type `MICResult` process result. If the asynchronous process started normally, returns `MIC_RESULT_SUCCESS`. If the process fails for some reason, returns some other value.

## Description

Asynchronously starts microphone auto-sampling. This function issues a request to the ARM7 processor to start auto-sampling and returns to the place from which it was called without waiting for a response from the ARM7 processor. To get the result from the processor, you must use the `result` argument. If the input volume exceeds the minimum or maximum value, the output data will be clamped. It is possible to set the input volume that can be sampled using the `PM_SetAmpGain` function.
If this function fails, asynchronous operations are not performed and the user callback function cannot be called.

## Caution

It is possible to operate other ARM7 processor peripherals (SPI device) during microphone auto-sampling. However, note that if another SPI device had taken over the access for a long time, the microphone would keep returning a certain value during that time.

## See Also

`MIC_StartAutoSampling`, `MIC_StopAutoSampling`, `MIC_StopAutoSamplingAsync`, `PM_SetAmpGain`

## Revision History

06/27/2005 Added statement about callbacks being called from the interrupt handler.
01/11/2005 Revised return values, revised description, added reference function.
09/17/2004 Changed the type for the argument `param`.
08/10/2001 Added the description to touch panel sampling during microphone auto sampling. Added the description regarding the input volume.
06/01/2004 Initial version.

CONFIDENTIAL