wm9708 Wolfson Microelectronics plc, wm9708 Datasheet - Page 26

• Manufacturer Part Number: wm9708
• Description: Ac?97 Revision 2.1 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

WM9708
REVISION 2.1 REGISTERS (INDEX 28h T0 58h)
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The part will remain in sleep mode with all its registers holding their static values. To wake up the
WM9708, the AC’97 controller will send a pulse on the sync line issuing a warm reset. This will
restart the WM9708’s digital interface (resetting PR4 to 0). The WM9708 can also be woken up with
a cold reset. A cold reset will cause a loss of values of the registers, as a cold reset will set them to
their default states. When a section is powered back on, the Powerdown Control/Status Register
(index 26h) should be read to verify that the section is ready (i.e. stable) before attempting any
operation that requires it.
Figure 14 The WM9708 Powerdown/Flow with Analogue Still Alive
Figure 14 illustrates a state when all the mixers will work with the static volume settings that are
contained in their associated registers. This is used when the user could be playing a CD (or external
LINEIN source) through WM9708 to the speakers but have most of the system in low power mode.
The procedure for this follows the previous except that the analogue mixer is never shut down.
POWERDOWN CONTROL/STATUS REGISTER (INDEX 26h)
Note that in order to go into ultimate low power mode, PR4 and PR5 are required to be set which
turns off the oscillator circuit. Asserting SYNC resets the PR4 and PR5 bit and re-starts the oscillator
in the same was as the AC link is restarted.
These registers are specified as to use in Revision 2.1 of the AC’97 specification and have the
following functions on the WM9708:
REGISTER 28h – EXTENDED AUDIO ID
The Extended Audio ID register is a read only register 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 value indicates the feature is supported.
Table 12 Extended Audio ID Register
DATA BIT
CDAC
SDAC
AMAP
LDAC
DRA
VRM
VRA
ID1
ID0
ADCs OFF
PR0
PR1 = 0 AND
FUNCTION
Variable rate audio support
Double rate audio support
Variable rate Mic ADC support
Centre DAC support
Surround DAC support
LFE DAC support
Slot to front DAC mapping support
Codec configuration – fixed in 9707
Not supported
DAC = 1
PR1 = 1
DACs OFF
PR1
PR2 = 0 AND
PR2 = 1
ANL = 1
ANALOGUE
OFF PR2
OR PR3
PR4 = 1
WARM RESET
DIGITAL I/F
OFF PR4
Not supported
ANY MODE
PD, Rev 4.2, August 2009
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0
0
0
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0
CODA LINK
SHUT OFF
Production Data
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