MC80F0424 Datasheet, PDF (100/135 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC80F0424/0432/0448
Preliminary
Main Program
service
TIMER 1
service
enable INT0
disable other
EI
Occur
TIMER1 interrupt
Occur
INT0
INT0
service
enable INT0
enable other
In this example, the INT0 interrupt can be serviced without any
pending, even TIMER1 is in progress.
Because of re-setting the interrupt enable registers IENH,IENL
and master enable “EI” in the TIMER1 routine.
Figure 19-7 Execution of Multi Interrupt
19.5 External Interrupt
The external interrupt on INT0, INT1, INT2 and INT3 pins are
edge triggered depending on the edge selection register IEDS (ad-
dress 0EE_H) as shown in Figure 19-8.
The edge detection of external interrupt has three transition acti-
vated mode: rising edge, falling edge, and both edge.
INT0 ~ INT3 are multiplexed with general I/O ports (R10, R11,
R12, R50). To use as an external interrupt pin, the bit of port se-
lection register PSR0 should be set to “1” correspondingly.
Example: To use as an INT0 and INT2
:
;**** Set external interrupt port as pull-up state.
LDM PU1,#0000_0101B
;
;**** Set port as an external interrupt port
LDM PSR0,#0000_0101B
;
;**** Set Falling-edge Detection
LDM IEDS,#0001_0001B
:
INT0 pin
INT1 pin
INT0IF
INT0 INTERRUPT
INT1IF
INT1 INTERRUPT
INT2 pin
INT2IF
INT2 INTERRUPT
INT3 pin
INT3IF
2 22
IEDS
[0EEH]
INT3 INTERRUPT
2
Edge selection
Register
Figure 19-8 External Interrupt Block Diagram
96
MAR. 2005 Ver 0.2