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2.5 Interrupt Operation
All P2C0, P5C0, P8C0 and P11C0 can be used as interrupt signal sources. Refer
to Sec. 2.1 & Sec. 2.7 for P2C0/P5C0/P8C0/P11C0 location. The interrupt of OME-
PIO-D96 is
level-trigger & Active_High. The interrupt signal can be inverted
or non-inverted
programmable. The procedures of programming are given as
follows:
1. make sure the initial level is High or Low
2. if the initial state is High Æ select the
inverted signal (Sec. 3.3.6)
3. if the initial state is Low Æ select the non-inverted signal (Sec. 3.3.6)
4. enable the INT function (Sec. 3.3.4)
5. If the interrupt signal is active Æ program will transfer into the interrupt
service routine Æ if INT signal is High now Æ select the inverted input
Æ if INT signal is Low now Æ select the non-inverted input
Refer to DEMO3.C & DEMO4.C for single interrupt source. Refer to
DEMO5.C for four interrupt sources.
If only one interrupt signal source is used, the interrupt service routine does not
have to identify the interrupt source. (Refer to DEMO3.C & DEMO4.C)
If there are more than one interrupt sources, the interrupt service routine has to
identify the active signals as follows: (Refer to DEMO5.C)
1. Read the new status of the interrupt signal source
2. Compare the new status with the old status to identify the active signals
3. If P2C0 is active, service P2C0 & non-inverter/inverted the P2C0 signal
4. If P5C0 is active, service P5C0 & non-inverted/inverted the P5C0 signal
5. If P8C0 is active, service P8C0 & non-inverted/inverted the P8C0 signal
6. If P11C0 is active, service P11C0 & non-inverted/inverted the P11C0 signal
7. Save the new status to old status
Note: If the interrupt signal is too short, the new status may be as same as old
status. So the interrupt signal must be hold-active until the interrupt service
routine is executed. This hold time is different for different operating systems.
The hold time can be as short as micro-second or as long as second. In general,
20ms is enough for most operating systems.
OME-PIO-D96 User Manual (Ver.1.1, Mar/2003) ---- 9