CS4237B Datasheet, PDF (101/114 Pages) Cirrus Logic – CrystalClear Advanced Audio System with 3D Sound

CS4237B
MIDI Interface
MIDOUT - MIDI Out Transmit Data, Output, 4mA drive
This output is used to send MIDI data serially out to a external MIDI device. Normally
connected to pin 12 of the joystick connector for use with breakout boxes.
MIDIN - MIDI In Receive Data, Input
This input is used to receive serial MIDI data from an external MIDI device. This pin should
have a 4.7 kΩ pullup attached and is normally connected to pin 15 of the joystick connector for
use with breakout boxes.
External FM Synthesizer Interface
SCS - Synthesizer Chip Select, Output, 4 mA drive
By default, SCS/UP is an active low output forced low when a valid address decode to an
external FM synthesizer, as defined in the Plug and Play configuration registers, has occurred.
When the internal FM synthesizer is enabled, this pin is no longer used as an FM synthesizer
chip select. This pin can be used for a hardware volume up pin by setting VCEN in the
Hardware Configuration data.
SINT - Synthesizer Interrupt, Input
This pin, XCTL1/SINT/ACDCS/DOWN, defaults to the XCTL1 output which is controlled by
the XCTL1 bit in the WSS register I10. If VCEN in the Hardware Configuration data is set, this
pin converts to the DOWN volume control function. If VCEN is zero, and ACDbase is never
programmed to a non-zero value, this pin can be changed to SINT input by connecting a 10 kΩ
resistor between the XIOW pin and SGND. The polarity of SINT can be programmed through
CTRLbase+1 register, the ISH bit, or the Hardware Configuration data. SINT defaults to an
active low input that should be driven by the external FM synthesizer interrupt output pin. This
pin can also be configured at a second CDROM Chip Select, ACDCS, to support the alternate
IDE CDROM decode. (See the CDROM section for more information.) The pin is switched to
the CDROM alternate chip select when VCEN is zero and the base address is first programmed
to non-zero through the E²PROM data or PnP commands.
External Peripheral Port
XD<7:1> - External Data Bus bits 7 through 1, Bi-directional, 4mA drive
These pins are used to transfer data between the ISA bus and external devices such as the
modem and CDROM. These pins are also multiplexed with two serial ports. A DSP serial port
can be connected through the XD4-XD1 pins. This interface is multiplexed onto these external
data bus pins OR the 2nd Joystick pins based on the SPS (Serial Port Switch) bit. The second
serial port connects to the CS9236 Single-Chip Wavetable Music Synthesizer and uses pins
XD7-XD5. This serial port is enabled via the WTEN bit. Both SPS and WTEN are located in
either C8 in the Control logical device, or the Global Configuration byte in the E²PROM
Hardware Configuration data.
DS213PP4
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