
IDT SMBus Interfaces
PES34H16 User Manual
6 - 6
October 30, 2008
Notes
SMBus errors may occur when accessing the serial EEPROM. If an error occurs, then it is reported in
the SMBus Status (SMBUSSTS) register. Software should check for errors before and after each serial
EEPROM access.
I/O Expanders
The PES34H16 utilizes external SMBus/I2C-bus I/O expanders connected to the master SMBus inter-
face for hot-plug and port status signals.
The PES34H16 is designed to work with Phillips PCA9555 compatible I/O expanders (i.e., PCA9555,
PCA9535, and PCA9539). See the Phillips PCA9555 data sheet for details on the operation of this device.
An external SMBus I/O expander provides 16 bit I/O pins that may be configured as inputs or outputs.
PES34H16 supports up to 11 external I/O expanders. Figure 6.5 summarizes the allocation of functions
to I/O expanders. I/O expanders zero through seven are used to provide general hot-plug I/O signals. I/O
expander eight provides link status outputs while I/O expander nine provides link activity LED status
outputs. I/O expander ten provides hot-plug power good status inputs.
I/O expander signals associated with LED control (i.e., link status and activity) are active low (i.e., driven
low when an LED should be turned on).
I/O expander signals associated with hot-plug signals are not inverted.
SMBus I/O
Expander
Section
Function
0
Lower
Port 1 hot-plug
Upper
Port 3 hot-plug
1
Lower
Port 2 hot-plug
Upper
Port 4 hot-plug
2
Lower
Port 5 hot-plug
Upper
Port 7 hot-plug
3
Lower
Port 6 hot-plug
Upper
Port 8 hot-plug
4
Lower
Port 9 hot-plug
Upper
Port 11 hot-plug
5
Lower
Port 10 hot-plug
Upper
Port 12 hot-plug
6
Lower
Port 13 hot-plug
Upper
Port 15 hot-plug
7
Lower
Port 14 hot-plug
Upper
reserved
8
Lower
Link status (ports 0 through 7)
Upper
Link status (ports 8 through 15)
Figure 6.5 I/O Expander Function Allocation (Part 1 of 2)
Содержание 89HPES34H16
Страница 10: ...IDT Table of Contents PES34H16 User Manual iv October 30 2008 Notes...
Страница 12: ...IDT List of Tables PES34H16 User Manual vi October 30 2008 Notes...
Страница 18: ...IDT Register List PES34H16 User Manual xii October 30 2008 Notes...
Страница 40: ...IDT Upstream Port Failover PES34H16 User Manual 2 6 October 30 2008 Notes...
Страница 86: ...IDT Power Management PES34H16 User Manual 7 4 October 30 2008 Notes...
Страница 172: ...IDT Configuration Registers PES34H16 User Manual 9 80 October 30 2008 Notes...