Force Computers PENT/CPCI-721, Руководство по установке

Страница: 115 / 126

Maps and Registers PENT/CPCI-720/2/3 Registers
PENT/CPCI-721 6 - 9
Hot Swap I
2
C Register CPCI Bus B
The I
2
C register is used for data transfer between the CPCI-720 and a
hot-swap controller on the backplane. The geographical address line
GA[3] is used as the CLK line. The geographical address line GA[4] is
used as the DIR and DATA_IN line.
Note: This function is supported starting from PCB revision 1.0.
Table 18: Hot Swap I
2
C Register B
Address: 0111
16
Bit Value Description Access Settings
0 DIR Specifies direction of data
transfer. r/w = 0
Data is written to
the data line.
= 1 (default)
Data is read from
the data line.
1 CLK Clock line of the I
2
C bus r/w
2 DATA_IN Stores current value of data
line. r
3 EN Enables line drivers and
pull-up resistors of the hot
swap I
2
C bus.
r/w = 0 (default)
The line drivers
are tristated and
the pull-up resis-
tors are disabled.
All register bits
can still be writ-
ten or read.
=1
The line drivers
and pull-up
resistors are
enabled.