Intel 8XC196MC User Manual
8XC196MC, MD, MH USER’S MANUAL
5-8
The interrupt service routine should read the PI_PEND (Figure 5-12 on page 5-23) register to de-
termine the source of the interrupt. Before executing the return instruction, the interrupt service
routine should check to see if any of the other interrupt sources are pending. Generally, PTS in-
terrupt service is not useful for multiplexed interrupts because the PTS cannot readily determine
the interrupt source.
termine the source of the interrupt. Before executing the return instruction, the interrupt service
routine should check to see if any of the other interrupt sources are pending. Generally, PTS in-
terrupt service is not useful for multiplexed interrupts because the PTS cannot readily determine
the interrupt source.
Figure 5-3. Flow Diagram for the OVRTM Interrupt
A3254-01
Set OVRTM
x
bit in PI_PEND
Is OVRTM
x
bit set in
PI_MASK
?
Yes
No
Timer
x
Overflows
Set OVRTM
bit in INT_PEND
OVRTM bit
is not set
in INT_PEND
Is OVRTM
bit set in
INT_MASK
?
Yes
No
OVRTM interrupt
is not generated
Generate
OVRTM interrupt
Read PI_PEND
to see which
timer overflowed