CS4239 Datasheet, PDF (58/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
CONTROL INTERFACE
The Control logical device includes registers for
controlling various functions of the part that are
not included in the other logical device blocks.
These functions include game port rate control
and programmable power management, as well
as extra mixing functions.
Control Register Interface
The Control logical device software interface oc-
cupies 8 I/O locations, utilizes 12-bit address
decoding, and is located at PnP address
’CTRLbase’. If the upper address bits, SA12-
SA15 are used, they must be 0 to decode a valid
address. This device can also support an inter-
rupt. Table 16 lists the eight Control registers.
Address
CTRLbase+0
CTRLbase+1
CTRLbase+2
CTRLbase+3
CTRLbase+4
CTRLbase+5
CTRLbase+6
CTRLbase+7
Register
Joystick Control
E²PROM Interface
Block Power Down
Control Indirect Address Reg.
Control Indirect Data Register
Control/RAM Access
RAM Access End
Global Status
Table 16. Control Logical Device Registers
E²PROM Interface
CTRLbase+1, Default = 1xxxx000
D7 D6 D5 D4 D3 D2 D1 D0
ICH rbc rbc
rbc
rbc DIN/ DOUT CLK
EEN
Joystick Control
CLK
CTRLbase + 0, Default = xx0x0x01
D7 D6 D5
D4 D3 D2 D1 D0
rbc rbc CONSW rbc
XTAL rbc JR1 JR0
This bit is used to generate the clock
for the Plug and Play E²PROM.
EEN must be set to 1 to make this
bit operational. A 1 sets the SCL pin
high and a 0 sets the SCL pin low.
JR1,0
XTAL
CONSW
Joystick rate control. Selects operating
speed of the joystick (changes the
trigger threshold for the X/Y coordi-
nates).
DOUT
00 - slowest speed
01 - medium slow speed
10 - medium fast speed
11 - fastest speed
DIN/EEN
Crystal Oscillator disable. When set, all
functions are disabled except access
to this register. All registers retain
their values in this power-down
mode.
controls host interrupt generation
when a context switch occurs
0 - no interrupt on context switch
ICH
1 - Control interrupt generated on
context switch
This bit is used to output serial data
to the Plug and Play E²PROM. EEN
must be set to 1 to make this bit op-
erational. A 0 causes SDA to go low.
A 1 releases SDA (open-drain).
When read (DIN), this bit reflects
the SDA pin, which should be serial
data output from the Plug and Play
E²PROM. EEN and DOUT must be
1 for this bit to function.
When written (EEN), enables the
E²PROM interface: CLK and DOUT
onto the SCL/SDA pins. Writing:
0 - E²PROM interface disabled
1 - E²PROM interface enabled
Interrupt polarity - CDROM. When set,
the CDINT pin is an active high sig-
nal. When low, CDINT is an active
low signal. This bits can be initial-
ized through the Hardware
Configuration data.
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