1060
11028E–ATARM–22-Apr-13
SAM9G46
44.7.5.3
Wake-up Triggered by the AC97 Controller
The AC97 Controller can wake up the AC97 Codec by issuing either a cold or a warm reset.
The AC97 Controller can also wake up the AC97 Codec by asserting AC97FS signal, however
this action should not be performed for a minimum period of four audio frames following the
frame in which the powerdown was issued.
44.7.5.4
Wake-up Triggered by the AC97 Codec
This feature is implemented in AC97 modem codecs that need to report events such as Caller-
ID and wake-up on ring.
The AC97 Codec can drive AC97RX signal from low to high level and holding it high until the
controller issues either a cold or a worm reset. The AC97RX rising edge is asynchronously
(regarding AC97FS) detected by the AC97 Controller. If WKUP bit is enabled in AC97C_IMR
register, an interrupt is triggered that wakes up the AC97 Controller which should then immedi-
ately issue a cold or a warm reset.
If the processor needs to be awakened by an external event, the AC97RX signal must be exter-
nally connected to the WAKEUP entry of the system controller.
Figure 44-7. AC97 Power-Down/Up Sequence
44.7.5.5
AC97 Codec Reset
There are three ways to reset an AC97 Codec.
44.7.5.6
Cold AC97 Reset
A cold reset is generated by asserting the RESET signal low for the minimum specified time
(depending on the AC97 Codec) and then by de-asserting RESET high. AC97CK and AC97FS
is reactivated and all AC97 Codec registers are set to their default power-on values. Transfers
on AC-link can resume.
The RESET signal will be controlled via a PIO line. This is how an application should perform a
cold reset:
Clear and set ENA flag in the AC97C_MR register to reset the AC97 Controller
Clear PIO line output controlling the AC97 RESET signal
Wait for the minimum specified time
Set PIO line output controlling the AC97 RESET signal
AC97CK, the clock provided by AC97 Codec, is detected by the controller.
AC97CK
AC97FS
TAG
Write to
0x26
Data
PR4
Power Down Frame
Sleep State
TAG
Write to
0x26
Data
PR4
Wake Event
Warm Reset
New Audio Frame
TAG
Slot1
Slot2
AC97TX
AC97RX
TAG
Slot1
Slot2