
IDT SMBus Interfaces
PES32NT24xG2 User Manual
12 - 15
January 30, 2013
Notes
System design recommendations:
–
I/O expander addresses and default output values may be configured during serial EEPROM
initialization. If I/O expander addresses are configured via the serial EEPROM, then the switch will
initialize the I/O expanders when normal device operation begins following the completion of the
fundamental reset sequence.
–
If the I/O expanders are initialized via serial EEPROM, then the data value for output signals
during the SMBus initialization sequence will correspond to those at the time the SMBus transac-
tions are initiated. It is not possible to toggle SMBus I/O expander outputs by modifying data
values during serial EEPROM initialization.
–
During a fundamental reset and before the I/O expander outputs are initialized, all I/O expander
output signals default to inputs. Therefore, pull-up or pull-down resistors should be placed on
outputs to ensure that they are held in the desired state during this period.
–
All hot-plug data value modifications that correspond to hot-plug outputs result in SMBus transac-
tions. This includes modifications due to partition upstream secondary bus resets and partition hot
resets.
–
I/O expander outputs are not modified when the device transitions from normal operation to a
fundamental reset. In systems where I/O expander output values must be reset during a funda-
mental reset, a PCA9539 I/O expander should be used.
Hot-Plug I/O Expanders 0 through 11
SMBus I/O
Expander
Bit
Type
Signal
Description
0 (I/O-0.0)
1
1.
I/O-x.y corresponds to the notation used for PCA9555 port x I/O pin y.
I
PxAPN
2
2.
Refer to Table 12.6 for the mapping of ports to IO expanders.
Port x attention push button input
1 (I/O-0.1)
I
PxPDN
Port x presence detect input
2 (I/O-0.2)
I
PxPFN
Port x power fault input
3 (I/O-0.3)
I
PxPWRGDN
Port x power good input
4 (I/O-0.4)
O
PxAIN
Port x attention indicator output
5 (I/O-0.5)
O
PxPIN
Port x power indicator output
6 (I/O-0.6)
O
PxPEP
Port x power enable output
7 (I/O-0.7)
O
PxRSTN
Port x reset output
8 (I/O-1.0)
I
PyAPN
Port y attention push button input
9 (I/O-1.1)
I
PyPDN
Port y presence detect input
10 (I/O-1.2)
I
PyPFN
Port y power fault input
11 (I/O-1.3)
I
PyPWRGDN
Port y power good input
12 (I/O-1.4)
O
PyAIN
Port y attention indicator output
13 (I/O-1.5)
O
PyPIN
Port y power indicator output
14 (I/O-1.6)
O
PyPEP
Port y power enable output
15 (I/O-1.7)
O
PyRSTN
Port y reset output
Table 12.5 Pin Mapping for I/O Expanders 0 through 11
Summary of Contents for PCI Express 89HPES32NT24xG2
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Page 24: ...IDT List of Tables PES32NT24xG2 User Manual xiv January 30 2013 Notes...
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Page 196: ...IDT Transparent Switch Operation PES32NT24xG2 User Manual 10 26 January 30 2013 Notes...
Page 244: ...IDT SMBus Interfaces PES32NT24xG2 User Manual 12 40 January 30 2013 Notes...
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Page 710: ...IDT JTAG Boundary Scan PES32NT24xG2 User Manual 25 12 January 30 2013 Notes...
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