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Workstation 5 Field Service Guide
Workstation 5 System Board Technical Descriptions
AC 97 Audio Interface
The AC’97 architecture provides for data transfer through individual frames
transmitted in a serial data stream. A Time Division Multiplexed (TDM)
scheme is used to allow multiple input and output streams as well as access to
the internal control registers. Each frame is divided into 12 out going and 12
incoming data frames or slots.
The Table below describes the function of each audio link signal at U9, the
audio codec.
Speaker and Line Outputs (REF: ABRD88, Sheet 28)
The speaker outputs of the codec drive U26, a LM4940 ‘Boomer’ series audio
amplifier. The LM4940 outputs,
SPK_R_OUT
and
SRK_L_OUT
drive system
board connectors CN9 and CN10 respectively. The speakers are mounted
internally, at the left and right sides of the case.
AUD_PWRON
, from a GPIO pin on Super IO #1, is pulled to ground by R405
and fed to the
SHUTDOWN
input of U9. The BIOS sets
AUD_PWRON
low
during a warm or cold boot to reduce speaker ‘pop.’
The
LINE_OUT_R
and
LINE_OUT_L
outputs are fed through a low-pass filter
to Line Out Jack CN3. The internal speakers remain active when the Line-Out
jack is used.
Signal Name
I/O
Description
AC97_SYNC
Input/Output
48 Khz sync pulse that indicates the
beginning of a serial transfer on
AC97_DATA_OUT and
AC97_DATA_IN.
AC97_BITCLK
Output
12.888 Mhz Serial Data Clock from
the codec. Derived from the
CLK_14_CODEC input at Pin-2.
AC97_DATA_OUT
Output
Audio Controller Serial Data Out.
Transmits audio data to the codec.
Data stream consists of both control
data and audio data. Data valid on
rising the rising edge of
AC97_BITCLK.
AC97_DATA_IN
Input
Audio Controller Serial Data In. Data
stream consists of both control data
and audio data. Data valid on rising
the rising edge of AC97_BITCLK.
PCI_RST#
Input
Working Domain Master Reset.
