UPD784224 Datasheet, PDF (46/92 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784224, 784225, 784224Y, 784225Y
8. INTERRUPT FUNCTION
As the servicing in response to an interrupt request, the three types shown in Table 8-1 can be selected by
program.
Table 8-1. Servicing of Interrupt Request
Servicing Mode
Vectored interrupt
Context switching
Macro service
Entity of Servicing
Software
Firmware
Servicing
Branches and executes servicing routine
(servicing is arbitrary).
Automatically switches register bank,
branches and executes servicing routine
(servicing is arbitrary).
Executes data transfer between memory
and I/O (servicing is fixed)
Contents of PC and PSW
Saves to and restores
from stack.
Saves to or restores from
fixed area in register bank
Retained
8.1 Interrupt Sources
Table 8-2 shows the interrupt sources available. As shown, interrupts are generated by 25 types of sources,
execution of the BRK instruction, BRKCS instruction, or an operand error.
The priority of interrupt servicing can be set to four levels, so that nesting can be controlled during interrupt
servicing and that which of the two or more interrupts that simultaneously occur should be serviced first. When the
macro service function is used, however, nesting always proceeds.
The default priority is the priority (fixed) of the service that is performed if two or more interrupt requests, having
the same request, simultaneously generate (see Table 8-2).
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Data Sheet U12376EJ1V0DS00