8169 Datasheet, PDF (22/30 Pages) STMicroelectronics – DIGITAL AUDIO PROCESSOR WITH MULTICHANNEL DDX™

STA304A
12.5 Extended Audio ID Register (add. 28h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 ID0 0
0
0
0
0
1
1
1
0
0
0
0
1
1
The Extended Audio ID is a read only register that identifies which extended audio features are supported (See
AC'97 revision 2.1 specification, section A.2.1). The extended features supported are Variable Rate PCM Audio
(VRA), Double- Rate PCM Audio (DRA), PCM Center (CDAC), PCM Surround (SDAC) and PCM LFE (LDAC).
Codec_ID0 report the status of SA pin. Codec_ID1 always report 0. Hence, the configurations are primary (00)
if SA pin is 0 or Secondary (01) if SA pin is 1.
12.6 Extended Audio Status and Control Register (add. 2Ah)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0
1
1
1
DRA VRA
• VRA= 1 enables Variable Rate Audio mode (sample rate control registers and SLOTREQ signaling)
• DRA= 1 enables Double- Rate Audio mode
Bits D9- D6 are read only status of the extended audio feature readiness. When a write request is issued the
actual data written into the RAM register is 'xxxxxx0111xxxxxx'.
For more details refer to AC’97 rev 2.1, section A.2.2
12.7 Audio Sample Rate Control Registers (add. 2Ch - 34h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0
In VRA mode, two frequencies are supported 48000(BB80h) Hz and 44100(AC44h) Hz. If one of these value
written to the 2Ch register, that value will be echoed back when read, otherwise the closest (higher in case of a
tie) sample rate supported is returned. The content of 2Eh and 30h registers is copied from the 2Ch register.
If the Double Rate Audio (DRA) mode is active, the sample rate programmed will be multiplied by 2x. For ex-
ample: When running at 88.2 kHz, the DRA bit will be programmed to 1, and the sample rate programmed would
be 44.100.
The default value after cold or warm register reset for these registers (BB80h) is 48 kHz.
The content of the ADC sample rate registers (32h and 34h) stays always BB80h.
12.8 6-Channel Volume Control Register (add. 36h - 38h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Mute LFE6 LFE5 LFE4 LFE3 LFE2 LFE1 LFE0 Mute CNT6 CNT5 CNT4 CNT3 CNT2 CNT1 CNT0
Mute LSR6 LSR5 LSR4 LSR3 LSR2 LSR1 LSR0 Mute RSR6 RSR5 RSR4 RSR3 RSR2 RSR1 RSR0
These read/write registers control the output volume of the optional four PCM channels, and values written to
the fields behave the same as the Play Master Volume Register (Index 02h), which offers attenuation but no
gain. There is an independent mute (1= on) for each channel.
The default value after reset for this registers (8080h) corresponds to 0 dB attenuation with mute on.
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