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Chapter 7
DMA Functions (DMA Controller)
Preliminary User’s Manual U15839EE1V0UM00
7.13 Precautions
(1)
Memory boundary
The transfer operation is not guaranteed if the source or the destination address exceeds the area
of DMA objects (internal RAM, or peripheral I/O) during DMA transfer.
(2)
Transfer of misaligned data
DMA transfer of 16-bit/32-bit bus width misaligned data is not supported.
(3)
Times related to DMA transfer
The overhead before and after DMA transfer and the minimum execution clock for DMA transfer
are shown below.
• Internal RAM access: 2 clocks
(4)
Bus arbitration for CPU
The CPU can access on-chip peripheral I/O, and internal RAM not undergoing DMA transfer.
While data transfer is being executed between internal RAMs, the CPU can access external mem-
ory and peripheral I/O.
(5)
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.
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