CS4237B Datasheet, PDF (102/114 Pages) Cirrus Logic – CrystalClear Advanced Audio System with 3D Sound

CS4237B
SDA/XD0 - External Data Bus bit 0/E²PROM Data Pin, Bi-directional, Open Drain,4mA sink
This open-drain pin must have an external pullup (3.3 kΩ) and is used to transfer data between
the ISA bus bit 0, SD0, and external devices such as a modem or CDROM. SDA/XD0 is also
used in conjunction with SCL/XA0 to access an external serial E²PROM. When an E²PROM is
used, the SDA/XD0 pin should be connected to the data pin of the E²PROM device and
provides a bi-directional data port. The E²PROM is used to set the Plug and Play resource data.
XCTL0/XA2 - XCTL0 or External Address SA2, Output, 4mA drive
This pin either outputs ISA bus address SA2 or XCTL0 depending on the Hardware
Configuration data. The default is XCTL0 which is controlled by the XCTL0 bit in the WSS
register I10. This pin changes to address bit XA2 if the Hardware Configuration data indicates
that the peripheral port requires more than four I/O addresses.
XA1 - External Address, Output, 4mA drive
This pin outputs ISA bus address SA1.
XA0/SCL - External Address, Output/Serial Clock, Output, 4mA drive
This pin outputs the ISA bus address SA0. When E²PROM access is enabled, via EEN in
CTRLbase+1, then SCL is used as a clock output to the E²PROM.
BRESET - Buffered Reset, Output, 4mA drive
This active low signal goes low whenever the RESDRV pin goes high. This pin is also software
controllable through the BRES bit in register C8 in the Control Logical Device space. BRES
provides a software power down and reset control over devices connected to the Crystal Codec
such as the CS9236 Single-Chip Wavetable Music Synthesizer.
XIOR - External Read Strobe, Output, 4mA drive (SA12-SA15/CDROM selection)
This active low signal goes low whenever (SCS, CDCS, or MCS) and IOR goes low. When
RESDRV goes low, this pin also selects either the CDROM/Modem port or SA12 - SA15 and
contains an internal pullup of approximately 100 kΩ. When XIOR is left high (default), pins
91-94 are SA15-SA12 respectively. To enable the CDROM and Modem ports, an external 10kΩ
resistor must be tied between this pin and SGND.
XIOW - External Write Strobe, Output, 4mA drive (XCTL1/SINT/ACDCS/DOWN selection)
This active low signal goes low whenever (SCS or CDCS or MCS) and IOW goes low. When
RESDRV goes low, this pin also selects either XCTL1 or SINT and contains an internal pullup
of approximately 100 kΩ. When XIOW is left high (default), pin 16 is the XCTL1 function (or
ACDCS, based on a non-zero value being programmed into the alternate CDROM address
register). To change the pin to SINT, an external 10kΩ resistor must be tied between this pin
and SGND.
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