Cirrus Logic CDB4271, Instruction Manual

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CDB4271
4
1. SYSTEM OVERVIEW
The CDB4271 demonstration board is an excellent means for evaluating the CS4271 stereo
CODEC. Analog and digital audio signal interfaces are provided, as well as a DB-25 computer
parallel port interface for use with the supplied Window
®
configuration software.
The CDB4271 schematic set has been partitioned into 10 pages and is shown in Figures 6
through 15.
1.1 CS4271 Stereo Audio CODEC
A complete description of the CS4271 is included in the CS4271 product data sheet.
1.2 CS8406 Digital Audio Transmitter
The operation of the CS8406 transmitter (see Figure 11) and a discussion of the digital audio
interface are included in the CS8406 data sheet.
The CS8406 converts the PCM data generated by the CS4271 to the standard S/PDIF data
stream. The CDB4271 is able to operate the CS8406 in either master or slave mode. The
serial audio input data for the CS8406 is received from the serial audio output of the CS4271.
Using the GUI, the user may elect to supply the CS8406 with an external serial audio data
source through a stake header (J17). Digital Interface format selection of either Left Justified
or I
2
S can be made via the control port GUI or via the I2S/LJ position on switch, S1
(see Table 2 for switch control options).
1.3 CS8416 Digital Audio Receiver
The operation of the CS8416 receiver (see Figure 10) and a discussion of the digital audio
interface are included in the CS8416 data sheet.
The CS8416 converts the input S/PDIF data stream into PCM data for the CS4271. The
CDB4271
is able to operate the CS8416 in master or slave mode. Digital Interface format se-
lection of either Left Justified or I
2
S can be made via the I2S/LJ position on S1. Left Justified,
I
2
S or Right Justified interface formats can be selected via the control port GUI.
The CS8416 always sources an MCLK signal. As a result, it should be noted that the CS8416
will provide invalid data in modes where the MCLK signal is generated by the CS4271 or re-
ceived through the stake header (J26). Care should be taken to ensure that the crystal (Y2)
is removed when the board is configured to receive MCLK from the CS8416.
The CS8416 contains an internal input multiplexer which must be set to receive the appropri-
ate stream from the Optical or Coaxial input connector. This may be done via the
Coaxial/Optical position on S1, or through the control port GUI.