AMD manual AMD Geode SC2200 Processor

32580B Core Logic Module

6.2.12.2 AC97 Codec Interface

The AC97 codec is the master of the serial interface and generates the clocks to Core Logic module. Figure 6-13shows the signal connections between two codecs and the SC2200:

•Codec1 can be AC97 Rev. 1.3 or higher compliant.

•Codec2 is optional, but must be compliant with AC97 2.0 or higher. (For specifics on the serial interface, refer to the appropriate codec manufacturer’s data book.):

—SDATA_IN2 has wakeup capability. (See Section 5.6 "System Wakeup Control (SWC)" on page 123.)

—If SDATA_IN2 is not used it must be connected to VSS.

—If an AMC97 codec is used (as Codec2), it should be connected to SDATA_IN2 and SDATA_IN should be connected to VSS.

•For PC speaker synthesis, the Core Logic module outputs the PC speaker signal on the PC_BEEP pin which is connected to the PC_BEEP input of the AC97 codec. Note that PC_BEEP is muxed with GPIO16 and must be programmed via PMR[0] (see Table 4-2 on page 76.)

Codec Configuration/Control Registers

The codec 32-bit related registers:

•GPIO Status and Control Registers:

—Codec GPIO Status Register (F3BAR0+Memory Offset 00h)

—Codec GPIO Control Register (F3BAR0+Memory Offset 04h)

•Codec Status Register (F3BAR0+Memory Offset 08h)

•Codec Command Register (F3BAR0+Memory Offset 0Ch)

Codec GPIO Status and Control Registers:

The Codec GPIO Status and Control registers are used for codec GPIO related tasks such as enabling a codec GPIO interrupt to cause an SMI.

Codec Status Register:

The Codec Status register stores the codec status WORD. It is updated every valid Status Word slot.

Codec Command Register:

The Codec Command register writes the control WORD to the codec. By writing the appropriate control WORDs to this port, the features of the codec can be controlled. The contents of this register are written to the codec during the Control Word slot.

The bit formats for these registers are given in Table 6-38 "F3BAR0+Memory Offset: Audio Configuration Registers" on page 273.

BIT_CLK

SYNC

PC_BEEP

SDATA_OUT SDATA_IN

AC97_CLK

BIT_CLK

XTAL_I

SYNC Codec1

PC_BEEP

SDATA_OUT

SDATA_IN

BIT_CLK

XTAL_I

SYNC

Codec2

AMD Geode™

SC2200

Processor

SDATA_IN2

(Optional)

PC_BEEP

SDATA_OUT

SDATA_IN2

Figure 6-13. AC97 V2.0 Codec Signal Connections

178 AMD Geode™ SC2200 Processor Data Book