Samsung S5PC110 Manual page 1882

S5PC110_UM
4.3.6.2 Waking up the AC-link - Wake Up Triggered by the AC97 Controller
AC-link protocol provides a cold AC97 reset and a warm AC97 reset. The current power-down state ultimately
dictates which AC97 reset is used. Registers must stay in the same state during all power-down modes unless a
cold AC97 reset is performed. In a cold AC97 reset, the AC97 registers are initialized to their default values. After
a power down, the AC-link must wait for a minimum of four audio frame times after the frame in which the power
down occurred before it can be reactivated by reasserting the SYNC signal. When AC-link powers up, Codec
ready bit (input slot 0, bit 15) indicates that AC-link is ready for operation.
PR0 = 1
Normal
PR0 = 0
&
ADC = 1
4.3.6.3 Cold AC97 Reset
A cold reset is generated when the nRESET pin is asserted through the AC_GLBCTRL. Asserting and
deasserting nRESET activates BITCLK and SDATA_OUT. All AC97 control registers are initialized to their default
power on reset values. nRESET is an asynchronous AC97 input.
4.3.6.4 Warm AC97 Reset
A Warm AC97 reset reactivates the AC-link without altering the current AC97 register values. A warm reset is
generated when BITCLK is absent and SYNC is driven high. In normal audio frames, SYNC is a synchronous
AC97 input. When BITCLK is absent, SYNC is treated as an asynchronous input used to generate a warm reset to
AC97.The AC97 Controller must not activate BITCLK until it samples SYNC low again. This prevents a new audio
frame being falsely detected.
PR1 = 1
ADCs off DACs off
PR0 PR1
PR1 = 0
&
DAC = 1
Ready = 1
Figure 4-8
PR2 = 1
Analog
off
PR2 or
PR3
PR2 = 0
&
ANL = 1
Default
AC97 Power down/Power up Flow
4 AC97 CONTROLLER
PR4 = 1
Digitial I/F
off
PR4
Warm Reset
Cold Reset
Shut off
AC-link
4-10