TP_RequestAutoSamplingStart

Syntax

#include <nitro/spi.h>
u32 TP_RequestAutoSamplingStart(
            u16 vcount,
            u16 frequence,
            TPData samplingBufs[],
            u16 bufSize );

Arguments

vcount Base V-count value for auto sampling.
frequence The number of samples taken during one frame (MAX 4).
samplingBufs The pointer that sets the buffer in which auto sampling values are stored.
bufSize The element count of the buffer passed by samplingBufs.

Return Values

Returns 0 if the request succeeds; returns non-zero value if it fails.

Description

This function issues a request to ARM7 to begin auto sampling touch panel values and waits for the request to complete internally. This is the synchronous version of the TP_RequestAutoSamplingStartAsync function. After this request is accepted, sampling is carried out periodically and values are stored in the array specified by samplingBufs. The autosampling interval is the interval at which VAlarm samples data uniformly, frequence times per frame, based on the value set in vcount.
However, the span of time over which the V-Count values range from 200 to 214 is not used for sampling. This is because the V-Count values may be changed by the GX_SetVCount function. If the V-count value to be sampled is contained in this interval, sampling is delayed until line 215.
If a user callback is set with the TP_SetCallback function, notification is given by a callback each time a value is saved. After this function clears samplingBufs, the buffer will be used as a loop buffer. The TP_GetLatestIndexInAuto function can be used to get the index of the data that was last saved. When auto-sampling, it is possible that  the sampling value for (newest index + 1) will be unexpectedly overwritten by an interrupt. If you are using the sampling values from one frame all together, you can avoid this by securing an area that is at least frequence + 1.

Note

This function uses an interrupt to wait for a completion response from ARM7. Notice that if it is called while FIFO receive interrupts from ARM7 are prohibited, it will not be possible to return from wait.

See Also

TP_RequestAutoSamplingStop, TP_GetLatestRawPointInAuto, TP_GetLatestCalibratedPointInAuto, TP_GetLatestIndexInAuto, TP_RequestAutoSamplingStartAsync, TPData

Revision History

2007/10/29 Added a description.
2007/10/16 Added an explanation of unused V-count values.
2006/09/01 Revised the description of bufSize.
2004/04/21 Made this a synchronous function and created an asynchronous version.
2004/04/16 Initial version.


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