
34
Preliminary Specifications
FlashFlex51 MCU
SST89E52RD2 / SST89E54RD2 / SST89E58RD2 / SST89E516RD2
SST89V52RD2 / SST89V54RD2 / SST89V58RD2 / SST89V516RD2
2004 Silicon Storage Technology, Inc.
S71255-00-000
3/04
Symbol
EX2
Function
External Interrupt 2
Enable bit if set
Interrupt Enable
If IT2=1, IE2 is set/cleared automatically by hardware when interrupt is detected/
serviced.
External Interrupt 2 is falling-edge/low-level triggered when this bit is cleared by 
software.
External Interrupt 3
Enable bit if set
Interrupt Enable
If IT3=1, IE3 is set/cleared automatically by hardware when interrupt is detected/
serviced.
External Interrupt3 is falling-edge/low-level triggered when this bit is cleared by 
software.
IE2
IT2
EX3
IE3
IT3
External Interrupt Control (XICON)
Location
AEH
7
0
6
5
4
3
0
2
1
0
Reset Value
00H
EX3
IE3
EX2
IE2
IT2