CS4239 Datasheet, PDF (86/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
MIDI Interface
MIDOUT - MIDI Out Transmit Data, Output, 4 mA 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, as well as on-board
synthesizers.
MIDIN - MIDI In Receive Data, Input - Internal Pullup
This input is used to receive serial MIDI data from an external MIDI device. This pin should be
connected to pin 15 of the joystick connector for use with breakout boxes.
External Peripheral Signals
SDA - E²PROM Data Pin, Bi-directional, Open Drain, 4 mA sink
This open-drain pin must have an external pullup (3.3 kΩ) and is used in conjunction with SCL
to access an external serial E²PROM. When an E²PROM is used, the SDA 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 - External Control, Output, 4 mA drive
This pin is a general purpose output pin controlled by the XCTL0 bit in the WSS register I10.
SCL - E²PROM Serial Clock, Output, 4 mA drive (Address Port Selection)
When E²PROM access is enabled, via EEN in CTRLbase+1, then SCL is used as a clock
output to the E²PROM. At power-up, this pin is an input (with an internal 100 kΩ pullup) that
selects between two alternate addresses for the Address Port used to configure the chip.
Assuming APSEL is strapped low, SCL high selects 308h as the Address Port, and when SCL is
tied low (with a 10 kΩ resistor to ground), the Address Port is 388h.
BRESET - Buffered Reset, Output, 4 mA 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 CS4239 such
as the CS9236 Single-Chip Wavetable Music Synthesizer.
86
DS253PP2