Texas Instruments PCM4201EVM, Руководство пользователя

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3.6 Audio Serial Port Interface
3.7 Digital Interface Transmitter
Hardware Description and Configuration
The PCM4201EVM audio serial port is accessed at header J3. The port includes the audio bit clock
(BCK), the audio frame synchronization clock (FSYNC), and the serial audio data (DATA). The system
clock (SCKI) is also available at the audio serial port. The audio serial port may be operated in Slave or
Master Mode.
In Slave Mode, the BCK, FSYNC, and SCKI clocks are inputs to the PCM4201EVM, and may be provided
from an external source (DSP, FPGA, etc.) via header J3. The BCK and FSYNC clocks must be
synchronous with one another and the audio data.
In Master Mode, the BCK, FSYNC, and SCKI clocks are outputs, being derived by the PCM4201 using the
on-board crystal oscillators or external clock source applied at connector J4.
The Slave or Master Mode port configuration is programmed using the S/M element of switch SW1.
Table 5 summarizes the available settings.
Table 5. Slave/Master Mode Configuration
S/M AUDIO SERIAL PORT SLAVE/MASTER MODE
LO Master
HI Slave
Slave or Master Mode audio serial port operation also dictates the required rate of the system clock
(SCKI) supported for various sampling modes. A summary of the supported rates is shown in
Table 6 and
Table 7 .
Table 6. System Clock Rates for Master Mode Operation
SCKI RATE SAMPLING MODE WITH MASTER MODE AUDIO SERIAL PORT
512f
S
Normal Speed Low Power
512f
S
Normal Speed High Performance
256f
S
Double Speed
Table 7. System Clock Rates for Slave Mode Operation
SCKI RATE SAMPLING MODE WITH SLAVE MODE AUDIO SERIAL PORT
256f
S
or 512f
S
Normal Speed Low Power
256f
S
or 512f
S
Normal Speed High Performance
256f
S
Double Speed
A Texas Instruments DIT4096 digital interface transmitter provides an AES3-encoded output for the
PCM4201EVM. The DIT and DITCLK elements of switch SW1 are utilized to configure the transmitter.
The output of the transmitter is available at connector J5. This output is designed for use with 75
Ω
coaxial
cable connections.
The transmitter is enabled using the DIT element of switch SW1. The DIT switch operation is summarized
in
Table 8 .
8 SBAU108A – January 2005 – Revised February 2005 PCM4201EVM User's Guide