CHAPTER 13 DMA FUNCTIONS
User’s Manual U15109EJ3V0UD
481
481
Figure 13-5. When Interrupt Servicing Occurs Twice During DMA Operation (1/2)
(a) Normal interrupt servicing
RETI
EI
Interrupt request
Main routine
Interrupt servicing routine
Interrupt request flag (xxIFn) is
cleared (0).
(b) Interrupt servicing when interrupt servicing occurs twice
EI
RETI
RETI
Interrupt request flag (xxIFn) is
cleared (0).
Main routine
Interrupt servicing routine
Interrupt request flag (xxIFn) is
not cleared and remains 1.
Bit manipulation
instruction to xxIFn
Interrupt request
Since the interrupt request flag
(xxIFn) remains 1, the interrupt
is serviced again.
Remark
xx: Identifying name of peripheral unit (see
Table 7-2
)
n: Peripheral unit number (see
Table 7-2
)