FUJITSU MB91F109 FR30 - Manual (Page 365)

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15.8 Notes on DMAC
itself continues.
■ External Transfer from Internal Memory
In block transfer mode, DMA transfer is performed twice for a single DREQ. In continuous
transfer mode, DMA transfer is performed even if DREQ is canceled. To prevent this, select
one of the following countermeasures:
• Use DREQs in edge detection mode (valid in block mode only).
• Set the transfer destination address in the external area to generate a DACK during access
to the transfer destination.
• Set descriptors in external memory unless both transfer source and destination addresses
are fixed.