ST72F324BJ STMICROELECTRONICS [STMicroelectronics], ST72F324BJ Datasheet - Page 182

• Manufacturer Part Number: ST72F324BJ
• Description: 8-bit MCU, 3.8 to 5.5 V operating range with 8 to 32 Kbyte Flash/ROM, 10-bit ADC, 4 timers, SPI, SCI
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Known limitations
15.1.3
15.1.4
Note:
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RIM ; reset the interrupt mask
LD A,sema ; check the semaphore status
CP A,#$01
jrne OUT
call call_routine ; call the interrupt routine
RIM
OUT:RIM
JP while_loop
.call_routine ; entry to call_routine
PUSH A
PUSH X
PUSH CC
.ext1_rt ; entry to interrupt routine
LD A,#$00
LD sema,A
IRET
Unexpected reset fetch
If an interrupt request occurs while a “POP CC” instruction is executed, the interrupt
controller does not recognize 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.
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.
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, that is, when:
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●
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If these conditions are not met, the symptom can be avoided by implementing the following
sequence:
Perform SIM and RIM operation before and after resetting an active interrupt request.
Example:
The interrupt flag is cleared within its own interrupt 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
–
–
–
SIM
Reset interrupt flag
RIM
ST72324B