CS4239 Datasheet, PDF (57/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
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.
The Game Port hardware interface consists of
8 pins that connect directly to the standard game
port connector. Buttons must have a 1000 pF ca-
pacitor to ground and have internal 20 kΩ
pullups resistors. X/Y coordinates must have a
5.6 nF capacitor to ground and a 2.2 kΩ series
resistor to the appropriate joystick connector pin.
Figure 5 illustrates the schematic to the joystick
connector.
CRYSTAL
CODEC
VDF
1
9
JAB1
2
JBB1
10
JACX
2.2 k Ω
3
JBCX
2.2 k Ω
11
5.6 nF
5.6 nF
1 nF
1 nF
4
12
JBCY
JACY
5
2.2 k Ω
13
2.2 k Ω
6
JBB2
14
JAB2
7
MIDOUT
15
5.6 nF 5.6 nF 1 nF 1 nF
8
MIDIN
Figure 5. Joystick Logic
DS253PP2
57