
5 C
ONFIGURATION
& O
PERATION
Data Sheet Revision 1.3
Page 13
OX16PCI954
OXFORD SEMICONDUCTOR LTD.
The OX16PCI954 is a multi-function, target-only PCI
device, compliant with the PCI Local Bus Specification,
Revision 2.2 and PCI Power Management Specification,
Revision 1.0.
The OX16PCI954 affords maximumconfiguration flexibility
by treating the internal UARTs, Local bus and the parallel
port as separate logical functions. Each function has its
own configuration space and is therefore recognised and
configured by the PCI BIOS seperately. The functions
used are configured by the Mode[1:0] pins as shown in
Table 3.
The OX16PCI954 is configured by systemstart-up
software during the bootstrap process that follows bus
reset. The systemscans the bus and reads the vendor and
device identification codes fromany devices it finds. It then
loads device-driver software according to this information
and configures the I/O, memory and interrupt resources.
Mode [1:0]
Configuration
00
Function 0 is Quad UART, Function 1 is 8-bit local bus
01
Function 0 is Quad UART, Function 1 is parallel port
10
Function 0 is Quad UART, Function 1 is unusable as the local bus pins are used to assign Subsystem
ID and SubsystemVendor ID to function 0
11
Function 0 is unusable, Function 1 is 32-bit local bus
Device drivers can then access the functions at the
assigned addresses in the usual fashion, with the improved
data throughput provided by PCI.
Each function operates as though it was a separate device;
however there are a set of Local configuration registers
that can be used to enable signals and interrupts, configure
timngs, and improve the efficiency of multi-port drivers.
This architecture enables separate drivers to be installed
for each function. Generic port drivers can be hooked to
use the functions individually, or more efficient multi-port
drivers can hook both functions, accessing the Local
Configuration Registers fromeither.
All registers default after reset to suitable values for typical
applications such a 4/8 port serial, or combo 4-port serial/1-
port parallel add-in cards. However, all identification,
control and timng registers can be redefined using an
optional serial EEPROM.
Table 3: Mode configuration