CS4235 Datasheet, PDF (44/94 Pages) Cirrus Logic – CrystalClear Low Cost ISA Audio System

CS4235
CrystalClear ^TM Low Cost ISA Audio System
WSS EXTENDED REGISTERS
The Windows Sound System codec contains
three sets of registers: R0-R3, I0-I31, and X0-
X31. R0-R3 are directly mapped to the ISA bus
through WSSbase+0 through WSSbase+3 re-
spectively. R0 and R1 provide access to the
indirect registers I0-I31. The third set of registers
are extended registers X0-X31 that are indirectly
mapped through the WSS register I23. I23 acts
as both the extended address and extended data
register. These extended registers are only avail-
able when in MODE 3.
Accessing the X registers requires writing the
register address to I23 with XRAE set. When
XRAE is set, I23 changes from an address regis-
ter to a data register. Subsequent accesses to I23
access the extended data register. To convert I23
back to the extended address register, R0 must
be written which internally clears XRAE. As-
suming the part is in MODE 3, the following
steps access the X registers:
1. Write 17h to R0 (to access I23).
R1 is now the extended address register.
2. Write the desired X register address to R1
with XRAE = 1.
R1 is now the extended data register.
3. Write/Read X register data from R1.
To read/write a different X register:
4. Write 17h to R0 again. (resets XRAE)
R1 is now the extended address register.
5. Write the new X register address to R1
with XRAE = 1.
R1 is now the new extended data register.
6. Read/Write new X register data from R1.
Address
WSSbase+0
WSSbase+1
Reg.
R0
R1
I23
Register Name
Reset Address
Address/Data access
Indexed Address/Data
Extended Register Access (I23)
D7 D6 D5 D4 D3 D2 D1 D0
XA3 XA2 XA1 XA0 XRAE XA4 res rbc
Table 11. WSS Extended Register Control
Index
X0
X1
X2
X3
X4
X5
X6
X7
X8
X9
X10
X11
X12
X13
X14
X15
X16
X17
X18
X19
X20
X21
X22
X23
X24
X25
X26
X27
X28
X29
X30
X31
Register Name
Reserved, backwards compatible
Reserved, backwards compatible
MIC Volume
MIC Volume (same as X2)
Synthesis and Input Mixer Control
Right Input Mixer Control
Left FM Synthesis Mute
Right FM Synthesis Mute
Left DSP Serial Port Mute
Right DSP Serial Port Mute
Reserved, backwards compatible
DAC1 Mute and IFSE Enable
Independent ADC Sample Freq.
Independent DAC Sample Freq.
Reserved, backwards compatible
Reserved, backwards compatible
Left Wavetable Serial Port Mute
Right Wavetable Serial Port Mute
3D Enable & RAM Port Enable
FM Volume Scaling
Reserved
Reserved
Reserved
(C2) 3D Space Control
(C8) Wavetable & Volume Control
Chip Version and ID
(Cb+0) Joystick Control
(Cb+1) E²PROM Interface
(Cb+2) Power Down Control 1
(C9) Power Down Control 2
(Cb+7) Global Status
Reserved
Table 12. WSS Extended Registers
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DS252PP2