HD6412350 Hitachi, HD6412350 Datasheet - Page 293

• Manufacturer Part Number: HD6412350
• Description: (HD6412350 / HD6432351) 16-BIT MICROCONTROLLER
• Manufacturer: Hitachi

7.5.14
Relation Between External Bus Requests, Refresh Cycles, the DTC, and the DMAC
There can be no break between a DMA cycle read and a DMA cycle write. This means that a
refresh cycle, external bus release cycle, or DTC cycle is not generated between the external read
and external write in a DMA cycle.
In the case of successive read and write cycles, such as in burst transfer or block transfer, a refresh
or external bus released state may be inserted after a write cycle. Since the DTC has a lower
priority than the DMAC, the DTC does not operate until the DMAC releases the bus.
When DMA cycle reads or writes are accesses to on-chip memory or internal I/O registers, these
DMA cycles can be executed at the same time as refresh cycles or external bus release. However,
simultaneous operation may not be possible when a write buffer is used.
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