C. System Registers
77
Geographic Addressing (E4h), continued
4:0
Geographic Addressing
CompactPCI defines several signal additions to the PCI specification. One of these
is GA[4..0], used for geographic addressing on the backplane. Geographic
addressing uniquely differentiates each board based upon the physical slot into
which it was inserted. Each backplane connector in a CompactPCI system has a
unique code for GA[4..0]. See the
CompactPCI Specification
, PICMG 2.0, Version
2.1
for more information on geographic addressing. The bits correspond to signals
as follows:
Bit 0
= GA0;
Bit 1
= GA1;
Bit 2
= GA2;
Bit 3
= GA3;
Bit 4
= GA4.
A logical 0 indicates that the corresponding GA pin is open. A logical 1 indicates that
the corresponding GA pin is low (GND).
Control Bits (E5h)
Address Offset:
E5h
Default Value:
0x00
Size: 8
bits
Attribute: W
Bit Description
7:0
RESERVED
J5 SMBus Enable (E6h)
Address Offset:
E6h
Default Value:
0x00
Size: 8
bits
Attribute: W
Bit Description
7
J5 SMBus Enable
This bit enables SMBus function through the rear panel J5 connector. A logical 1
enables this function.
6:0
RESERVED
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