ST72325
15 KNOWN LIMITATIONS
15.1 ALL DEVICES
15.1.1 Unexpected Reset Fetch
If an interrupt request occurs while a “POP CC” in-
struction is executed, the interrupt controller does
not recognise the source of the interrupt and, by
default, passes the RESET vector address to the
CPU.
Workaround
To solve this issue, a “POP CC” instruction must
always be preceded by a “SIM” instruction.
15.1.2 Clearing active interrupts outside
interrupt routine
When an active interrupt request occurs at the
same time as the related flag is being cleared, an
unwanted reset may occur.
Note: clearing the related interrupt mask will not
generate an unwanted reset
Concurrent interrupt context
The symptom does not occur when the interrupts
are handled normally, i.e.
when:
– The interrupt flag is cleared within its own inter-
rupt routine
– The interrupt flag is cleared within any interrupt
routine
– The interrupt flag is cleared in any part of the
code while this interrupt is disabled
If these conditions are not met, the symptom can
be avoided by implementing the following se-
quence:
Perform SIM and RIM operation before and after
resetting an active interrupt request.
Example:
SIM
reset interrupt flag
RIM
Nested interrupt context:
The symptom does not occur when the interrupts
are handled normally, i.e.
when:
– The interrupt flag is cleared within its own inter-
rupt routine
– The interrupt flag is cleared within any interrupt
routine with higher or identical priority level
– The interrupt flag is cleared in any part of the
code while this interrupt is disabled
If these conditions are not met, the symptom can
be avoided by implementing the following se-
quence:
PUSH CC
SIM
reset interrupt flag
POP CC
190/193