CS4237B Datasheet, PDF (15/114 Pages) Cirrus Logic – CrystalClear Advanced Audio System with 3D Sound

CS4237B
INTERRUPTS
For Plug-and-Play flexibility, six interrupt pins
are supported, although only one or two are typi-
cally used. The default hardware connections,
which can be modified through the hardware
configuration data, are:
IRQ A = ISA Interrupt 5
IRQ B = ISA Interrupt 7
IRQ C = ISA Interrupt 9
IRQ D = ISA Interrupt 11
IRQ E = ISA Interrupt 12
IRQ F = ISA Interrupt 15
The typical configuration would support two in-
terrupt sources: one shared between the WSS
Codec and the Sound Blaster Pro compatible de-
vices, and the other for the MPU401 device.
Interrupts are also supported for the Synthesizer,
Control, CDROM devices, but are typically not
used. If the modem logical device (LD5) is used,
it would typically support an interrupt.
PLUG AND PLAY
The Plug-and-Play (PnP) interface logic is com-
patible with the Intel/Microsoft Plug-and-Play
specification, version 1.0a, for an ISA-bus de-
vice. Since the part is an ISA-bus device, it only
supports ISA-compatible IRQs and DMA chan-
nels. Plug and Play compatibility allows the PC
to automatically configure the part into the sys-
tem upon power up. Plug and Play capability
optimally resolves conflicts between Plug and
Play and non-Plug and Play devices within the
system. Alternatively, the PnP feature can be by-
passed. See the Bypassing PnP section for more
information. For a detailed Plug-and-Play proto-
col description, please refer to the Plug and Play
ISA Specification.
To support Plug-and-Play in ISA systems that do
not have a PnP BIOS or a PnP-aware operating
system, the Configuration Manager (CM) TSR
and an ISA Configuration Utility (ICU) from In-
tel Corp. are used to provide these functions.
DS213PP4
The CM isolates the cards, assigns Card Select
Numbers, reads PnP card resource requirements,
and allocates resources to the cards based on
system resource availability. The ICU is used to
keep the BIOS and the CM informed of the cur-
rent system configuration. It also aids users in
determining configurations for non-PnP ISA
cards. A more thorough discussion of the Con-
figuration Manager and the ISA Configuration
Utility can be found in the Product Development
Information document of the Plug and Play Kit
by Intel Corp. In a PnP BIOS system, the BIOS
is responsible for configuring at least all system
board PnP devices. Some systems require addi-
tional software to aid the BIOS in configuring
PnP ISA cards. The PnP BIOS can execute all
PnP functions independently of the type of oper-
ating system. However, if a PnP aware operating
system is present, the PnP responsibilities are
shared between the BIOS and the operating sys-
tem. For more information regarding PnP BIOS,
please refer to the latest revision of the Plug and
Play BIOS Specification published by Compaq
Computer, Phoenix Technologies, and Intel.
The Plug and Play configuration sequence maps
the various functional blocks of the part (logical
devices) into the host system address space and
configures both the DMA and interrupt channels.
The host has access to the part via three 8-bit
auto-configuration ports: Address port (0279h),
Write Data port (0A79h), and relocatable Read
Data port (020Bh - 03FFh). The read data port is
relocated automatically by PnP software when a
conflict occurs.
The configuration sequence is as follows:
1. Host sends a software key which places all
PnP cards in the sleep state (or Plug-and-
Play mode).
2. The Crystal part is isolated from the system
using an isolation sequence.
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