cs4237b Cirrus Logic, Inc., cs4237b Datasheet - Page 60

• Manufacturer Part Number: cs4237b
• Description: Crystalclear Advanced Audio System With 3d Sound
• Manufacturer: Cirrus Logic, Inc.

GAME PORT INTERFACE
The Game Port logical device software interface
utilizes 10-bit address decoding and is located at
PnP address ’GAMEbase’. 10-bit addressing re-
quires that the upper address bits be 0 to decode
a valid address, i.e. no aliasing occurs. For back-
wards compatibility, the Game Port consists of 8
I/O locations where the lower 6 alias to the same
location, which consists of one read and one
write register.
Plug and Play configuration capability will allow
the joystick I/O base address, GAMEbase, to be
located anywhere within the host I/O address
space. Currently most games software assume
that the joystick I/O port is located at 200h.
A write to the GAMEbase register triggers four
timers. A read from the same register returns
four status bits corresponding to the joystick fire
buttons and four bits that correspond to the out-
put from the four timers.
A button value of 0 indicates the button is
pressed or active. The button default state is 1.
When GAMEbase is written, the X/Y timer bits
go high. Once GAMEbase is written, each timer
output remains high for a period of time deter-
mined by the current joystick position. The
number in parenthesis below is the joystick con-
nector pin number.
GAMEbase+0 - GAMEbase+5
JACX
JACY
JBCX
JBCY
60
JBB2
D7
JBB1
D6
JAB2
D5
Joystick A, Coordinate X (pin 3)
Joystick A, Coordinate Y (pin 6)
Joystick B, Coordinate X (pin 11)
Joystick B, Coordinate Y (pin 13)
JAB1
D4
JBCY
D3
JBCX
D2
JACY
D1
JACX
D0
JAB1
JAB2
JBB1
JBB2
Two bits, JR1 and JR0, are located in the Con-
trol register space (CTRLbase+0) for defining
the speed of the Game Port Interface. Four dif-
ferent rates are software selectable for use with
various joysticks and to support older software
timing loops with aliasing (roll-over) problems.
GAMEbase+6
res
GAMEbase+7
res
The Game Port hardware interface consists of
8 pins that connect directly to the standard game
port connector. Buttons must have a 4.7 k
lup resistor and a 1000 pF capacitor to ground.
X/Y coordinates must have a 5.6 nF capacitor to
ground and a 2.2 k
priate joystick connector pin. For a detailed
hardware description, see the Reference Design
Data Sheet.
D7
D7
res
res
D6
D6
res
res
D5
D5
res
res
Must not write any value to this
register. May read any value.
Must not write any value to this
register. May read any value.
Joystick A, Button 1 (pin 2)
Joystick A, Button 2 (pin 7)
Joystick B, Button 1 (pin 10)
Joystick B, Button 2 (pin 14)
D4
D4
res
res
series resistor to the appro-
D3
D3
res
res
D2
D2
res
res
CS4237B
D1
D1
res
res
DS213PP4
D0
D0
res
res
pul-