WM9705_06 WOLFSON [Wolfson Microelectronics plc], WM9705_06 Datasheet - Page 34

• Manufacturer Part Number: WM9705_06
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM9705
REGISTER 28h – EXTENDED AUDIO ID
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Figure 16 illustrates one example procedure to do a complete Powerdown of the WM9705. From
normal operation sequential writes to the Powerdown Register are performed to Powerdown the
WM9705 a piece at a time. After everything has been shut off (PR0 to PR3 set), a final write (of
PR4) can be executed to shut down the WM9705’s digital interface (AC-link).
The part will remain in sleep mode with all its registers holding their static values. To wake up the
WM9705, the AC’97 controller will send a pulse on the sync line issuing a warm reset. This will
restart the WM9705’s digital interface (resetting PR4 to 0). The WM9705 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 17 The WM9705 Powerdown Flow with Analogue Still Active
Figure
are contained in their associated registers. This is used when the user could be playing a CD (or
external LINEIN source) through WM9705 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.
The device can be used as a pen digitiser only, in order to set the WM9705 into this mode
powerdown bits PR3 to 0, PR6 and EAPD should be set.
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 bit and re-starts the oscillator in the
same way as the AC link is restarted.
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.
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illustrates a state when all the mixers should work with the static volume settings that
NORMAL
PR0 = 0 AND
ADC = 1
PR0 = 1
ADC’s OFF
PR0
PR1 = 0 AND
PR1 = 1
DAC = 1
DACs OFF
PR1
PR4 = 1
WARM RESET
DIGITAL I/F
OFF PR4
PD Rev 4.4 August 2006
CODA LINK
SHUT OFF
Production Data
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