CS4281 Programming Manual
DS308PRM1
167
Confidential Draft
3/7/00
18. SOUND SYSTEM INTERFACE
The Sound System Interface provides all the regis-
ters and controls to operate the entire sound system.
The Sound System is the hardware that processes
data from the sample FIFOs to the AC Link. This
includes the AC Link side FIFO controls, sample
rate conversion, hardware volume control, and
FIFO exception handling functions. The Sound
System registers are logically located in this block.
In the CS4281, the codec/mixer analog registers
are accessed through the AC Link. All Sound Sys-
tem registers are PCI memory mapped.
18.1
Sound System Register Interface
18.1.1
Sound System Power Management (SSPM)
Address:
BA0: 740h
Default:
00000000h
Definition: Enables for FM, Joystick, AC Link, and SRCs. When disabled, each device consumes minimal
power.
Bit Descriptions:
MIXEN
When set, the digital mixer is enabled and data coming out of the Playback SRC is mixed with
FM or Wavetable data before going to the AC Link. When clear, the Digital Mixer and PSRC
are bypassed.
CSRCEN
When set, the capture sample rate converter is enabled. When clear, the CSRC is powered
down; however, the output latch is still used if the SRC is assigned a slot number.
PSRCEN
When set, the playback sample rate converter is enabled. When clear, the PSRC is powered
down; however, the output latch is still used if the SRC is assigned a slot number.
MIXEN
must
be set when
PSRCEN
is set.
JSEN
When set, joystick logic is enabled. When clear, joystick logic powered down and coordinate
input circuits are disabled, input clamp transistors are disabled, and the joystick registers are
read-only with a value of 0. Therefore, if a joystick is attached, the pin will float up to Vcc
reducing power. If no joystick is attached, the coordinate pins will float but the input circuit is
disabled to stop excess current from flowing into the pad.
ACLEN
When set, serial port engine and AC-Link are enabled. When clear, both are powered down
FMEN
When set, FM synthesis block is enabled and mixed with the PCM output stream connected to
the playback SRC. When clear, FM synthesis block is powered down and the digital stream is
available for Host wavetable.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
MIXEN
CSRCE
N
PSRCE
N
JSEN
ACLEN
FMEN
D
ra
ft
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