CS4235 Datasheet, PDF (87/94 Pages) Cirrus Logic – CrystalClear Low Cost ISA Audio System

CS4235
CrystalClear ^TM Low Cost ISA Audio System
CDINT - CDROM Interrupt, Input
This pin is used to input an interrupt signal from the CDROM interface. The part can be
programmed, through the plug-and-play resource data, to output this signal to the appropriate
ISA bus interrupt line. The polarity if this input can be programmed through CTRLbase+1
register, bit ICH, or the Hardware Configuration data; the default is active high.
CDRQ - CDROM DMA Request, Input
This pin can be used to input the DMA request signal from the CDROM interface. The part can
be programmed, through the plug-and-play resource data, to output this signal to the
appropriate ISA bus DRQ line.
CDACK- CDROM DMA Acknowledge, Output, 4 mA drive
This pin can be used to output the ISA bus-generated DMA acknowledge signal to the CDROM
interface.
Volume Control
The volume control pins are enabled by setting VCEN in the Hardware Configuration data,
Misc. Hardware Config. byte. The VCF1 bit in the Hardware Configuration data, Global
Configuration byte, set the format for the volume control pins. Typically a 100 Ω series resistor
and a 10 nF capacitor (required) to ground, capacitor on the switch side of the series resistor,
would be included on each pin for ESD protection and to help with EMI emissions.
UP - Volume Up, Input - Internal Pullup
This pin is enabled when VCEN is set. When UP is low, the master volume output is
incremented. A 10 nF capacitor to ground is required for switch debounce.
DOWN - Volume Down, Input - Internal Pullup
The XCTL1/ACDCS/DOWN is a multiplexed pin that can be used as XCTL1, the alternate
CDROM chip select, or the Volume Down pin. This pin is switched to the DOWN function
when VCEN is set. When DOWN is low, the master volume output is decremented. A 10 nF
capacitor to ground is required for switch debounce.
MUTE - Volume Mute, Input - Internal Pullup
The MUTE pin function can be momentary, or non-existent based on the VCF1 bit. The MUTE
function is enabled when VCEN is set. A 10 nF capacitor to ground is required for switch
debounce.
Miscellaneous
XTALI - Crystal Input
This pin will accept either a crystal, with the other pin attached to XTALO, or an external
CMOS clock. XTAL must have a crystal or clock source attached for proper operation. The
crystal frequency must be 16.9344 MHz and designed for fundamental mode, parallel resonance
operation.
DS252PP2
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