CS4281 Datasheet, PDF (11/36 Pages) Cirrus Logic – CrystalClear PCI Audio interface

CS4281
CrystalClear™ PCI Audio Interface
CPU
North
Bridge
Host
Memory
PCI Bus
South
Bridge
CS4281
PCI Audio Interface
AC-Link
PC/PCI
(if used)
CS4298
Audio Out
Audio In
DAA
Telephone
Line
Figure 7. Modem Scenario
HOST INTERFACE
The CS4281 host interface is comprised of two separate interface blocks which are memory mapped into
host address space. The interface blocks can be located anywhere in the host 32-bit physical address space.
The interface block locations are defined by the addresses programmed into the two Base Address Regis-
ters in the PCI Configuration Space. These base addresses are normally set up by the system’s Plug and
Play BIOS. The first interface block (Base Address 0) contains the general purpose configuration, control,
and status registers for the device. The second interface block (Base Address 1) maps the FIFO RAMs into
host memory space. The relationship between the Base Address Registers in the CS4281 PCI Configura-
tion Space and the host memory map is depicted in Figure 8. The bus mastering PCI bus interface complies
with the PCI Local Bus Specification (version 2.1).
Device PCI Config. Space
00h Device ID / Vendor ID
04h Status / Command
08h Class Code / Revision
0Ch
Misc. Control
10h Base Address Register 0
14h Base Address Register 1
Direct Registers
(Memory Mapped, 4 kByte)
Direct Memory Interface
(Memory Mapped, 64 kByte)
Figure 8. Host Interface Base Address Registers
CIRRUS LOGIC PRODUCT DATA SHEET
DS308PP4
11