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9<TITLE>MIC_AdjustLimitedSampling</TITLE>
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14<H1 align="left">MIC_AdjustLimitedSampling <img src="../../image/TWL.gif"></H1>
15
16<H2>Syntax</H2>
17<DL>
18  <DD>
19<CODE>#include &lt;twl/spi.h&gt;</CODE><BR>
20  <PRE><CODE><A href="MICResult.html">MICResult</A> MIC_AdjustLimitedSampling( u32 rate );</CODE></PRE>
21  </DD>
22</DL>
23
24<H2>Arguments</H2>
25<TABLE border="1" width="100%">
26  <TBODY>
27    <TR>
28      <TD width="300"><em><strong><font face="Courier New">rate</font></strong></em></TD>
29      <TD width="700">Specifies the sampling frequency.</TD>
30    </TR>
31  </TBODY>
32</TABLE>
33
34<H2>Return Values</H2>
35<P>
36Returns the processing result as a <CODE><A href="MICResult.html">MICResult</A></CODE> enumerated type. Returns <CODE>MIC_RESULT_SUCCESS</CODE> if processing completed successfully; returns some other value if the process failed.
37</P>
38
39<H2>Description</H2>
40<P>
41Synchronously adjusts the sampling rate of the frequency-limited microphone auto-sampling.<BR>This function issues a request to the ARM7 to adjust frequency-limited auto-sampling, waits for the ARM7 to respond, and then returns the processing result. This is a synchronous version of the <CODE><A href="MIC_AdjustLimitedSamplingAsync.html">MIC_AdjustLimitedSamplingAsync</A></CODE> function. This function is only valid when frequency-limited auto-sampling has already begun. The sampling cycle is updated when the ARM7 receives the request, no earlier.
42</P>
43<P>
44Frequency-limited auto-sampling differs from normal auto-sampling in that the hardware does the actual sampling. As a result, stable sampling can be performed at precise cycles; also, by relaxing the CPU burden on the ARM7, effects of sampling on wireless communications and other I/O will be reduced. On the other hand, sampling cannot be performed at frequencies that are unsupported by the hardware. The following sampling frequencies can be specified for <CODE>rate</CODE>, but the frequencies that can be specified at a given time depend on the sound master frequency settings and thus are further limited to four of the following. A value of <CODE>MIC_RESULT_ILLEGAL_PARAMETER</CODE> will be returned if one of the limited frequencies is not specified.
45</P>
46<TABLE border="1" width="100%">
47  <TBODY>
48    <TR>
49      <TH width="20%"><center>Sound master frequency</center></TD>
50      <TH width="40%"><center>Settable frequency</center></TD>
51      <TH width="40%"><center>Description</center></TD>
52    </TR>
53    <TR>
54      <TD rowspan="4">32.73kHz</TD>
55      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_32730</font></strong></em></TD>
56      <TD>32.73kHz (1/1 of the master frequency)</TD>
57    </TR>
58    <TR>
59      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_16360</font></strong></em></TD>
60      <TD>16.36kHz (1/2 of the master frequency)</TD>
61    </TR>
62    <TR>
63      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_10910</font></strong></em></TD>
64      <TD>10.91kHz (1/3 of the master frequency)</TD>
65    </TR>
66    <TR>
67      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_8180</font></strong></em></TD>
68      <TD>8.18kHz (1/4 of the master frequency)</TD>
69    </TR>
70    <TR>
71      <TD rowspan="4">47.61kHz</TD>
72      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_47610</font></strong></em></TD>
73      <TD>47.61kHz (1/1 of the master frequency)</TD>
74    </TR>
75    <TR>
76      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_23810</font></strong></em></TD>
77      <TD>23.81kHz (1/2 of the master frequency)</TD>
78    </TR>
79    <TR>
80      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_15870</font></strong></em></TD>
81      <TD>15.87kHz (1/3 of the master frequency)</TD>
82    </TR>
83    <TR>
84      <TD><em><strong><font face="Courier New">MIC_SAMPLING_RATE_11900</font></strong></em></TD>
85      <TD>11.90kHz (1/4 of the master frequency)</TD>
86    </TR>
87  </TBODY>
88</TABLE>
89
90<H2>Note</H2>
91<P>
92<FONT color=red>This function waits for a PXI interrupt for synchronization purposes. Do not call it when PXI interrupts are prohibited.<BR> <BR>Because frequency-limited auto-sampling cannot be performed on the NITRO platform or when the CODEC is running in CODEC-DS mode, this function will instead internally call the <CODE><A href="MIC_AdjustAutoSampling.html">MIC_AdjustAutoSampling</A></CODE> auto-sampling control function.</FONT>
93</P>
94<P><FONT color=red>It has been confirmed that slight hardware noise is mixed with the microphone input on the TWL console. See <A href="./about_HardwareNoise.html">here</A> for a workaround.</FONT></P>
95<H2>See Also</H2>
96<P>
97<CODE><A href="MIC_AdjustLimitedSamplingAsync.html">MIC_AdjustLimitedSamplingAsync</A>, <A href="MIC_StartLimitedSampling.html">MIC_StartLimitedSampling</A>, <A href="MIC_StopLimitedSampling.html">MIC_StopLimitedSampling</A></CODE>
98</P>
99
100<H2>Revision History</H2>
101<P>
1022008/01/09 Added a note about the difference in behavior with CODEC mode. <BR>2007/11/17 Initial version.<BR>
103</P>
104<hr><p>CONFIDENTIAL</p></body>
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