Table 13.3 I/O Expander Function Allocation - Renesas IDT 89HPES48H12G2 User Manual

IDT SMBus Interfaces
Notes
PES48H12G2 User Manual
PES48H12G2 supports up to 14 external I/O expanders. Table 13.3 summarizes the allocation of func-
tions to I/O expanders. 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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
During PES48H12G2 initialization, the SMBus/I2C-bus address allocated to each I/O expander used in
that system configuration should be written to the corresponding IO Expander Address (IOE[13:0]ADDR)
field. The IOExADDR fields are contained in the IO Expander Address (IOEXPADDR[3:0]) registers.
Hot-plug outputs and I/O expanders may be initialized via serial EEPROM. Since the I/O expanders and
serial EEPROM both utilize the master SMBus, no I/O expander transactions are initiated until serial
EEPROM initialization completes. Since no I/O expander transactions are initiated until serial EEPROM
initialization completes, it is not possible to toggle a hot-plug output through serial EEPROM initialization
(i.e., it is not possible to cause a 0 -> 1 -> 0 transition or a 1 -> 0 -> 1 transition).
Whenever the value of an IOEXPADDR field is written, SMBus write transactions are issued to the
corresponding I/O expander by PES48H12G2 to configure the device. This configuration initializes the
direction of each I/O expander signal and sets outputs to their default value.
Section
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower / Upper
Lower / Upper
Lower / Upper
Lower / Upper
Lower / Upper
Lower / Upper

Table 13.3 I/O Expander Function Allocation

13 - 6
Function
Port 0 hot-plug
Port 2 hot-plug
Port 1 hot-plug
Port 3 hot-plug
Port 4 hot-plug
Port 6 hot-plug
Port 5 hot-plug
Port 7 hot-plug
Port 8 hot-plug
Unused
Port 9 hot-plug
Unused
Port 12 hot-plug
Unused
Port 13 hot-plug
Unused
Hot-plug MRL inputs
Ports 0 through 7 hot-plug
electromechanical interlock
Ports 8, 9, 12, 13 hot-plug
electromechanical interlock
Partition fundamental reset inputs
Link status
Link activity
April 5, 2013