Cirrus Logic CDB48500-USB, Руководство пользователя, Страница: 27 / 52

4-3
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Copyright 2008 Cirrus Logic , Inc. DS784DB1
Basic Application Download and System Configuration for PCM Pass-through
CDB48500--USB Evaluation Kit Guide
4.2.2 Changing the Audio Input Source
The audio input to the DSP is selected through the “Audio In” block in DSP Composer. The Audio can be
delivered to the DSP via the following:
• 1. S/PDIF
• 2. 8ch ADC
• 3. USB
• 4. 12-channel ADC (Currently not supported)
4.2.2.1 Audio In via S/PDIF
To deliver data to the DSP via S/PDIF, drag the Audio In block to the work space and select “SPDIF” as
the Input Source. Double click the Audio In block to see the signal flow. Right Click on SPDIF Rx. The
device properties of the S/PDIF IN element lets you select if the SPDIF input is on SPDIF_RXP (Optical
In) or on SPDIF_RXN (Coaxial). The Input FS depends on input stream and must not be changed. The
Master/Slave property must always be set to Master to indicate that the S/PDIF transmitter masters
MCLK, SCLK and LRCLK as described in
Section 3.1.11.2, “Clock and Data Flow for S/PDIF Input” on
page 3-7 . The Audio In module with S/PDIF In as the input source is shown in Figure 4-3 .
Figure 4-3. Audio In via S/PDIF In
4.2.2.2 Audio In via 8-channel ADC
To deliver data to the DSP via 8ch ADC, drag the Audio In block to the work space and select “Analog (8
ch)” as the Input Source. Double click the Audio In block to see the signal flow. The device properties of
the Analog (8 ch) element lets you select if the sampling frequency of the ADC on the CS42448 CODEC.
The Master/Slave property must always be set to Master to indicate that the ADC will master SCLK and
LRCLK as described in
Section 3.1.11.1, “Clock and Data Flow for up to 8 Channel ADC inputs” on page
3-6 . The Audio In module with Analog (8-channel) as the input source is shown in Figure 4-4 .