Chapter 1
Introduction
DAS-429PCI/Mx: User’s Manual
page 1 - 13
The Base Address Registers are used by the system BIOS to determine the
number, size and base addresses of memory pages required by the board, within
host address space.
The host determines the page base addresses by interrogating these registers
after BIOS power-up initialization. Bit zero of each field is used to select whether
the space required is to be decoded as memory (bit 00 = 0) or I/O (bit 00 = 1). The
absolute base addresses of these pages are determined from information written
back to the Base Address Registers, by the BIOS (see also “Determining Base
Address Size”).
Up to five memory pages are required by the
DAS-429PCI/Mx
: one for each
ARINC-429 module present and one for the PC Global Interrupt Control
Registers (see the table below).
Note:
The contents of Base Address Register 0 are not loadable from nvRAM.
DETERMINING BASE ADDRESS SIZE
The address space defined by a given base address register is determined by
writing all 1s to a given base address register from the PCI bus and then reading
that register back. The number of 0s returned starting from D4 for memory space
and D2 for I/O space toward the high-order bits reveals the amount of address
space desired. The table below gives the required nvRAM/EPROM boot values
corresponding to Pages 1–4.
.
1.5.11
Base Address Registers (BADR)
Address:
10, 14, 18, 1C, 20, 24 (H)
Power-up value:
FFFFFFC1 H for offset 10 H; 00000000 H for all other registers
Boot-load:
External nvRAM offset 50 H, 54 H, 58 H, 5C H, 60 H (BADRO–4)
Attribute:
Read/Write: high bits; Read only: Low bits
Size:
32 bits
Register
Offset
Size
Function
Base Address Register 0 (PAGE 0)
10H
64Byte
PCI Global Interrupt Control Registers
Base Address Register 1 (PAGE 1)
14H
32Kb
ARINC-429 Module 0
Base Address Register 2 (PAGE 2)
18H
32Kb
ARINC-429 Module 1
Base Address Register 3 (PAGE 3)
1CH
32Kb
ARINC-429 Module 2
Base Address Register 4 (PAGE 4)
20H
32Kb
ARINC-429 Module 3
Base Address Registers Definitions
PAGE
nvRAM Offset
nvRAM Contents
PAGE 1
50 H
FFFF8000 H
PAGE 2
54 H
FFFF8000 H
PAGE 3
58 H
FFFF8000 H
PAGE 4
5C H
FFFF8000 H
Table 1-1
Address nvRAM/EPROM Boot Values
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