IDT Installation of the EB12N3 Eval Board
SMBus Interfaces
EB12N3 Eval Board Manual (18-597-001)
2 - 9
November 2, 2006
Notes
SMBus Interfaces
The PES12N3 contains two SMBus interfaces: a slave SMBus interface and a master SMBus interface.
The slave SMBus interface allows a SMBus Master device (such as the Intel E7520) full access to all soft-
ware-visible registers. The Master SMBus interface provides connection to the external serial EEPROMs
used for initialization and the I/O expander used for hot-plug signals. Six pins make up each of the two
SMBus interfaces. These pins consist of an SMBus clock pin, an SMBus data pin, and 4 SMBus address
pins.
SMBus Slave Interface
The System Management Bus (SMBus) is a two-wire interface through which various system compo-
nent chips can communicate. See Table 2.12. It is based on the principles of operation of I
2
C. Implementa-
tion of the SMBus signals in the PCI Express connector is optional and may not be present on the host
system. On the PES12N3 board, the slave SMBus interface is accessible through the PCI Express edge
connector as well as a 4-pin header as described in Table 2.12.
Note: The SMBus signals to the PCI
Express edge connector is disabled by default. To enable them, place 0-ohm resistors at locations R34 and
R35.
.
A fixed slave SMBus address specified by the SSMBADDR[5,3:1] pins is used.
For a fixed address, the SMBus address of the PES12N3 slave interface is
0b1110111
by default and is
configurable using the jumpers W1, W5, W2, and W3 as described in Tables 2.13 and 2.14.
J2[4]
SWMODE[2]
ON
J2[5]
SWMODE[3]
ON
J2[8]
<RESERVED>
ON
Slave SMBus Interface Connector
W20
Pin
Signal
1
N/C
2
SCL
3
GND
4
SDA
Table 2.12 Slave SMBus Interface Connector
Slave Interface Address Configuration
Address Bit
Signal
1
SSMBUSADDR[1]
2
SSMBUSADDR[2]
3
SSMBUSADDR[3]
Table 2.13 SMBus Slave Interface Address Configuration (Part 1 of 2)
Boot Configuration Vector Switches J1 & J2 (ON=0, Off=1)
Switch
BCV Bit
Default
Table 2.11 Boot Configuration Vector Switches (Part 2 of 2)
Содержание 89EBPES12N3
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