MATLAB XPC TARGET 4 - DEVICE DRIVERS User's Guide download pdf (Page 26)

2 PCI Drivers

PCI Bus Considerations

In this section...

“Introduction” on page 2-2

“PCI Configuration Space API” on page 2-3

“Memory-Mapped A ccesse s” on pag e 2-6

“I/O Port Accesses” on page 2-6

Introduction

When writing xPC Target drivers for PCI dev ices , consider the memory access

method. A PCI device can be either I/O port mapped or m e mory mapped.

• I/O port m apped — The BIOS assig ns a port range.

• Memory mapped — The BIOS assigns a memory region, if your device

is memory mapped.

The PC BIOS automatically assigns a conflict-free set of resources to any PCI

device found in the system at boot-up. You typically do not know w here the

board resides (base address) before driver initialization. However, you can

obtain this informa t ion by querying the PCI configuration s pac e at run time.

The xPC Target software provides functions to accomplish this (see the “PCI

Configuration Information” on page 10-2 functions).

To locate a PCI device, you need the following:

• Vendor and device ID

• Optionally, subsystem vendor and subsystem device ID

Note You need the subsystem vendor and subsystem device ID if the

vendor and device ID do not uniquely identify the board.

• Slot number or bus and slot number

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MATLAB XPC TARGET 4 - DEVICE DRIVERS User's Guide Page 26