Notes
PES12N3 User Manual
7 - 1
June 7, 2006
Chapter 7
SMBus Interfaces
Introduction
The PES12N3 contains two SMBus interfaces. The slave SMBus interface provides full access to all
software visible registers in the PES12N3, allowing every register in the device to be read or written by an
external SMBus master. The slave SMBus may also be used to initialize the serial EEPROM used for initial-
ization. The Master SMBus interface provides connection for an optional external serial EEPROM used for
initialization and an optional 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. As shown in Figure 7.1, the master and slave SMBuses may
be used in a unified or split configuration.
Figure 7.1 SMBus Interface Configuration Examples
In the unified configuration, shown in Figure 7.1(a), the master and slave SMBuses are tied together and
the PES12N3 acts both as an SMBus master as well as an SMBus slave on this bus. This requires that the
external SMBus master or processor that has access to PES12N3 registers support SMBus arbitration. In
Processor
PES12N3
SSMBCLK
SSMBDAT
MSMBCLK
MSMBDAT
SMBus
Master
Other
SMBus
Devices
Serial
EEPROM
Processor
PES12N3
SSMBCLK
SSMBDAT
MSMBCLK
MSMBDAT
SMBus
Master
Other
SMBus
Devices
Serial
EEPROM
...
...
(a) Unified Configuration
(b) Split Configuration
Hot-Plug
I/O
Expander
Hot-Plug
I/O
Expander
Summary of Contents for 89HPES12N3
Page 10: ...IDT Table of Contents PES12N3 User Manual iv June 7 2006 Notes...
Page 14: ...IDT List of Figures PES12N3 User Manual viii June 7 2006 Notes...
Page 36: ...IDT Clocking Reset and Initialization Reset PES12N3 User Manual 2 8 June 7 2006 Notes...
Page 40: ...IDT Link Operation Slot Power Limit Support PES12N3 User Manual 3 4 June 7 2006 Notes...
Page 50: ...IDT Switch Operation Switch Core Errors PES12N3 User Manual 4 10 June 7 2006 Notes...
Page 54: ...IDT Power Management Active State Power Management PES12N3 User Manual 5 4 June 7 2006 Notes...
Page 62: ...IDT Hot Plug and Hot Swap Hot Swap PES12N3 User Manual 6 8 June 7 2006 Notes...
Page 78: ...IDT SMBus Interfaces Slave SMBus Interface PES12N3 User Manual 7 16 June 7 2006 Notes...
Page 148: ...IDT Test and Debug SerDes Test Clock PES12N3 User Manual 10 6 June 7 2006...
Page 158: ...IDT JTAG Boundary Scan Usage Considerations PES12N3 User Manual 11 10 June 7 2006 Notes...