13-2
Intel® PXA255 Processor
Developer’s Manual
AC’97 Controller Unit
13.3
Signal Description
The AC’97 signals form the AC-link, which is a point-to-point synchronous serial interconnect that
supports full-duplex data transfers. All digital audio streams, Modem line CODEC streams, and
command/status information are communicated over the AC-link. The AC-link uses General
Purpose I/Os (GPIOs). Software must reconfigure the GPIOs to use them as the AC-link. The AC-
link pins are listed and described in
Table 13-1
.
13.3.1
Signal Configuration Steps
1. Configure SYNC and SDATA_OUT as outputs.
2. Configure BITCLK, SDATA_IN_0, and SDATA_IN_1 as inputs.
3. nACRESET is a dedicated output. It remains asserted on power-up. Complete these steps to
deassert nACRESET:
a. Configure the other AC’97 signals as previously described.
b. In the Global Control Register (GCR), Set the GCR[COLD_RST] bit. Refer to
Table 13-7
for more details.
Note:
Refer to
Section 4.1.3, “GPIO Register Definitions” on page 4-6
for details on programing the
GPDR and GAFR for use with the ACUNIT.
13.3.2
Example AC-link
Figure 13-1
shows an example interconnect for an AC-link. The ACUNIT supports one or two
CODECs on the AC-link. SDATA_IN_1 is not needed if only a Primary CODEC is connected.
Table 13-1. External Interface to CODECs
Name
Direction
Description summary
nACRESET
O
Active-low CODEC reset. The CODEC’s registers reset when
nACRESET is asserted.
GP28/BITCLK
I
12.288 MHz bit-rate clock.
GP31/SYNC
O
48 kHz frame indicator and synchronizer.
GP30/SDATA_OUT
O
Serial audio output data to CODEC for digital-to-analog conversion.
GP29/SDATA_IN_0
I
Serial audio input data from Primary CODEC.
GP32/SDATA_IN_1
I
Serial audio input data from Secondary CODEC.
Summary of Contents for PXA255
Page 1: ...Intel PXA255 Processor Developer s Manual January 2004 Order Number 278693 002 ...
Page 24: ...xxiv Intel PXA255 Processor Developer s Manual Contents ...
Page 30: ...1 6 Intel PXA255 Processor Developer s Manual Introduction ...
Page 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Page 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Page 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Page 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Page 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Page 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
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