PCM9211
SBAS495 –JUNE 2010
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DIR: Audio Port Sampling Frequency Calculator
The second sampling frequency calculator can be used to calculate the sampling frequency of DIR, ADC,
AUXIN0, AUXIN1, AUXIN2, Main Output Port, AUX Output Port, and DIT Input. Figure 29 illustrates the sampling
frequency calculator sources.
PFSTGT[2:0]
DIR (default)
000
001
010
011
100
101
110
111
ADC
AUXIN0
Audio Port
Sampling Frequency
Calculator
AUXIN1
AUXIN2
Main Output Port
AUX Output Port
DIT
Figure 29. Sampling Frequency Calculator Sources
The calculated sampling frequency fS is decoded to 4-bit data and stored in the PFSOUT[3:0] register. The input
source of this counter is selectable from AUXIN0, AUXIN1, AUXIN2, DIR, ADC, Main Output Port, AUX Output
Port, and DIT by using the Register 37h/PFSTGT[3:0].
To use this function, a 24.576-MHz clock source must be supplied to the XTI pin. The 24.576-MHz clock is used
as a reference clock. If the XTI pin is connected to DGND, the calculation is not performed. If there is an error in
the XTI clock frequency, the calculation result and range will be incorrect.
Register 38h/PFSST indicates the calculator status. It is recommended that PFSST is checked (for complete
status) before reading PFSOUT[3:0].
36
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