ABOV SEMICONDUCTOR MC81F4204 - 12.2 Procedure for External Interrupts

MC81F4204
April 24, 2012 Ver.1.41 87
EINTF
EXTERNAL INTERRUPT FLAG REGISTER 00CDH
7 6 5 4 3 2 1 0
EINTFH
EXT0IF EXT2IF EXT4IF EXT7IF EXT8IF EXT9IF EXT10IF EXT11IF
Reset value: 00H
R/W R/W R/W R/W R/W R/W R/W R/W
EXT0IF
EXT0 External Interrupt Flag
EXT2IF
EXT2 External Interrupt Flag
EXT4IF
EXT4 External Interrupt Flag
EXT7IF
EXT7 External Interrupt Flag
EXT8IF
EXT8 External Interrupt Flag
EXT9IF
EXT9 External Interrupt Flag
EXT10IF
EXT10 External Interrupt Flag
EXT11IF
EXT11 External Interrupt Flag
0: Not generated
1: Generated
12.2 Procedure
To generate external interrupt, following steps are required,
1. Prepare external interrupt sub-routine.
2. Set external interrupt pins to read mode
3. Enable the external interrupt and select the edge mode.
4. Make sure global interrupt is enabled(use ‘EI’ instruction).
After finish above steps, the external interrupt sub-routine is calling, when the edge is detected.
When the generated external interrupt is one of the external interrupt group, the EINTF register is
used to recognize which external interrupt is generated.