Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0

5.8 Extended Audio Register Set

The extended audio registers support variable sample rate audio output and input, double-rate audio output,

multichannel audio output, and S/PDIF output.

Reg Name D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default

28h Extended Audio ID ID1 ID0 x x REV1 REV0 AMAP LDAC SDAC CDAC DSA1 DSA0 VRM SPDIF DRA VRA xxxxh

2Ah Ext’d Audio Stat/Ctrl VCFG PRL PRK PRJ PRI SPCV MADC LDAC SDAC CDAC SPSA1 SPSA0 VRM SPDIF DRA VRA xxxxh

2Ch PCM Front DAC Rate SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h

2Eh PCM Surr DAC Rate SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h

30h PCM LFE DAC Rate SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h

32h PCM L/R ADC Rate SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h

34h Mic ADC Rate SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h

36h Center/LFE Volume Mute x LFE5 LFE4 LFE3 LFE2 LFE1 LFE0 Mute x CNT5 CNT4 CNT3 CNT2 CNT1 CNT0 8080h

38h Surr Volume Mute x LSR5 LSR4 LSR3 LSR2 LSR1 LSR0 Mute x RSR5 RSR4 RSR3 RSR2 RSR1 RSR0 8080h

3Ah S/PDIF Control V DRS SPSR1 SPSR0 L CC6 CC5 CC4 CC3 CC2 CC1 CC0 PRE COPY /AUDIO PRO 2000h

Table 30. AC ‘97 Extended Audio Register Set

5.8.1 Extended Audio ID Register (Index 28h)

Reg Name D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default

28h Extended Audio ID ID1 ID0 x x REV1 REV0 AMAP LDAC SDAC CDAC DSA1 DSA0 VRM SPDIF DRA VRA xxxxh

The Extended Audio ID is a read only register (except for the new bits D5 and D4, which are read/write) that

identifies which extended audio features are supported (in addition to the original AC ‘97 features identified by

reading the Reset Register at Index 00h). A non-zero Extended Audio ID value indicates one or more of the

extended audio features are supported.

• VRA=1 indicates optional Variable Rate PCM Audio is supported

• DRA=1 indicates optional Double-Rate PCM Audio output is supported

• SPDIF=1 indicates optional S/PDIF transmitter is supported. S/PDIF PCM is defined in IEC958

(IEC60958), encoded multichannel (AC-3, MPEG, DTS, etc.) is defined in IEC61937. The recently

published Amendment 1 to IEC60958-3 contains a proposal for higher sample rate support.

• VRM=1 indicates optional Variable Rate MIC input is supported

• DSA[1,0] are read/write bits that control optional DAC Slot Assignment as described in Table 32

• CDAC=1 indicates optional PCM Center DAC is supported

• SDAC=1 indicates optional PCM Surround L&R DACs are supported

• LDAC=1 indicates optional PCM LFE DAC is supported

• AMAP=1 indicates support for slot/DAC mappings based on Codec ID

• REV[1:0]=10 indicates Codec is AC ’97 revision 2.3 compliant. Codec compliant to older revisions will

have REV[1:0] set as indicated in Table 31 AC'97 Revision ID.