CHAPTER 13 DMA FUNCTIONS
User’s Manual U15109EJ3V0UD
482
Figure 13-5. When Interrupt Servicing Occurs Twice During DMA Operation (2/2)
(c) Countermeasure (use condition (i))
EI
DI
EI
RETI
The interrupt is serviced in the EI state
(interrupt enable state) (the interrupt is
not serviced immediately after bit
manipulation instruction execution).
Main routine
Interrupt servicing routine
Interrupt request flag (xxIFn) is
cleared (0).
Bit manipulation
instruction to xxIFn
Interrupt request
(d) Countermeasure (use condition (ii))
EI
EI
RETI
Interrupt request
Main routine
Interrupt servicing routine
Interrupt request flag (xxIFn) is
not cleared (0) and remains 1.
Bit manipulation
instruction to xxIFn
xxIFn is cleared
(0) at the start of
the interrupt
servicing routine
Remark
xx: Identifying name of peripheral unit (see
Table 7-2
)
n: Peripheral unit number (see
Table 7-2
)