#include <twl/spi.h>MICResult MIC_AdjustLimitedSampling( u32 rate );| rate | Specifies the sampling frequency. |
Returns the processing result as a MICResult enumerated type. Returns MIC_RESULT_SUCCESS if processing completed successfully; returns some other value if the process failed.
Synchronously adjusts the sampling rate of the frequency-limited microphone auto-sampling.
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 MIC_AdjustLimitedSamplingAsync 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.
Frequency-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 rate, 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 MIC_RESULT_ILLEGAL_PARAMETER will be returned if one of the limited frequencies is not specified.
| 32.73kHz | MIC_SAMPLING_RATE_32730 | 32.73kHz (1/1 of the master frequency) |
| MIC_SAMPLING_RATE_16360 | 16.36kHz (1/2 of the master frequency) | |
| MIC_SAMPLING_RATE_10910 | 10.91kHz (1/3 of the master frequency) | |
| MIC_SAMPLING_RATE_8180 | 8.18kHz (1/4 of the master frequency) | |
| 47.61kHz | MIC_SAMPLING_RATE_47610 | 47.61kHz (1/1 of the master frequency) |
| MIC_SAMPLING_RATE_23810 | 23.81kHz (1/2 of the master frequency) | |
| MIC_SAMPLING_RATE_15870 | 15.87kHz (1/3 of the master frequency) | |
| MIC_SAMPLING_RATE_11900 | 11.90kHz (1/4 of the master frequency) |
This function waits for a PXI interrupt for synchronization purposes. Do not call it when PXI interrupts are prohibited.
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 MIC_AdjustAutoSampling auto-sampling control function.
It has been confirmed that slight hardware noise is mixed with the microphone input on the TWL console. See here for a workaround.
MIC_AdjustLimitedSamplingAsync, MIC_StartLimitedSampling, MIC_StopLimitedSampling
2008/01/09 Added a note about the difference in behavior with CODEC mode.
2007/11/17 Initial version.
CONFIDENTIAL