IDT SMBus Interfaces
PES24N3A User Manual
6 - 11
April 10, 2008
Notes
Slave SMBus Interface
The slave SMBus interface provides the PES24N3A with a configuration, management and debug inter-
face. Using the slave SMBus interface, an external master can read or write any software visible register in
the device.
Initialization
Slave SMBus initialization occurs during a fundamental reset (see section Fundamental Reset on page
2-4). During the fundamental reset initialization sequence, the slave SMBus address is initialized. The
address is specified by the SSMBADDR[5,3:1] signals as shown in Table 6.8.
SMBus Transactions
The slave SMBus interface responds to the following SMBus transactions initiated by an SMBus master.
See the SMBus 2.0 specification for a detailed description of these transactions.
–
Byte and Word Write/Read
–
Block Write/Read
Initiation of any SMBus transaction other than those listed above to the slave SMBus interface produces
undefined results. Associated with each of the above transactions is a command code. The command code
format for operations supported by the slave SMBus interface is shown in Figure 6.5 and described in Table
6.9.
10 (I/O-1.2)
O
P2ACTIVEN
Port 2 activity output
11 (I/O-1.3)
O
Reserved
Tie high or low
12 (I/O-1.4)
O
P4ACTIVEN
Port 4 activity output
13 (I/O-1.5)
O
Reserved
Tie high or low
14 (I/O-1.6)
O
Reserved
Tie high or low
15 (I/O-1.7)
O
Reserved
Tie high or low
1.
I/O-x.y corresponds to the notation used for PCA9555 port x I/O pin y.
Address Bit
Address Bit Value
1
SSMBADDR[1]
2
SSMBADDR[2]
3
SSMBADDR[3]
4
0
5
SSMBADDR[5]
6
1
7
1
Table 6.8 Slave SMBus Address When a Static Address is Selected
SMBus I/O
Expander
Bit
Type
Signal
Description
Table 6.7 I/O Expander 4 Signals
Содержание 89HPES24N3A
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Страница 18: ...IDT Register List PES24N3A User Manual xii April 10 2008 Notes...
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