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S3C80M4/F80M4
INTERRUPT
STRUCTURE
5-15
INTERRUPT SOURCE POLLING SEQUENCE
The interrupt request polling and servicing sequence is as follows:
1. A source generates an interrupt request by setting the interrupt request bit to "1".
2. The CPU polling procedure identifies a pending condition for that source.
3. The CPU checks the source's interrupt level.
4. The CPU generates an interrupt acknowledge signal.
5. Interrupt logic determines the interrupt's vector address.
6. The service routine starts and the source's pending bit is cleared to "0" (by hardware or by software).
7. The CPU continues polling for interrupt requests.
INTERRUPT SERVICE ROUTINES
Before an interrupt request is serviced, the following conditions must be met:
— Interrupt processing must be globally enabled (EI, SYM.0 = "1")
— The interrupt level must be enabled (IMR register)
— The interrupt level must have the highest priority if more than one levels are currently requesting service
— The interrupt must be enabled at the interrupt's source (peripheral control register)
When all the above conditions are met, the interrupt request is acknowledged at the end of the instruction cycle.
The CPU then initiates an interrupt machine cycle that completes the following processing sequence:
1. Reset (clear to "0") the interrupt enable bit in the SYM register (SYM.0) to disable all subsequent interrupts.
2. Save the program counter (PC) and status flags to the system stack.
3. Branch to the interrupt vector to fetch the address of the service routine.
4. Pass control to the interrupt service routine.
When the interrupt service routine is completed, the CPU issues an Interrupt Return (IRET). The IRET restores
the PC and status flags, setting SYM.0 to "1". It allows the CPU to process the next interrupt request.
Содержание S3C80M4/F80M4
Страница 1: ...S3C80M4 F80M4 8 BIT CMOS MICROCONTROLLERS USER S MANUAL Revision 1 ...
Страница 44: ...ADDRESS SPACES S3C80M4 F80M4 2 20 NOTES ...
Страница 84: ...CONTROL REGISTERS S3C80M4 F80M4 4 26 NOTES ...
Страница 102: ...INTERRUPT STRUCTURE S3C80M4 F80M4 5 18 NOTES ...
Страница 190: ...INSTRUCTION SET S3C80M4 F80M4 6 88 NOTES ...
Страница 202: ...RESET and POWER DOWN S3C80M4 F80M4 8 6 NOTES ...
Страница 216: ...8 BIT TIMER 0 S3C80M4 F80M4 11 4 NOTES ...
Страница 220: ...8 BIT PULSE WIDTH MODULATION S3C80M4 F80M4 12 4 NOTES ...
Страница 230: ...ELECTRICAL DATA S3C80M4 F80M4 13 10 NOTES ...
Страница 248: ...DEVELOPMENT TOOLS S3C80M4 F80M4 16 8 NOTES ...
Страница 249: ...This datasheet has been downloaded from www DatasheetCatalog com Datasheets for electronic components ...