CHAPTER 6 DMA FUNCTIONS (DMA CONTROLLER)
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User’s Manual U14492EJ3V0UD
(6) Execution of program and DMA transfer in internal RAM
If the following conditions are both met, the CPU may deadlock due to conflicting operations of the internal
bus (during deadlock, only reset is acknowledged (NMI and interrupt are not acknowledged)). If only either
one of the conditions is met, the CPU will not deadlock.
[Occurrence conditions]
•
Execution of DMA transfer for the internal RAM
•
Execution of a bit manipulation instruction (SET1, CLR1, or NOT1) allocated to the internal RAM, or data
access instruction to a misaligned address
Prevent deadlock using one of the following methods.
[Prevention methods]
•
Do not execute instructions allocated to the internal RAM if executing DMA transfer for the internal RAM.
•
Do not execute DMA transfer for the internal RAM if executing instructions allocated to the internal RAM.
6.14.1 Interrupt factors
DMA transfer is interrupted if a bus hold is issued.
If the factor (bus hold) interrupting DMA transfer disappears, DMA transfer promptly restarts.
Содержание V850E/IA1 mPD703116
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