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Chapter 6
DMA Functions (DMA Controller)
Preliminary User’s Manual U14913EE1V0UM00
6.12 DMA
Transfer
End
6.12.1 DMA transfer end interrupt
When DMA transfer ends and the TCn bit of the DCHCn register is set to 1, a DMA transfer end inter-
rupt (INTDMAn) is issued to the interrupt controller (INTC) (n = 0 to 3).
6.12.2 Terminal count output upon DMA transfer end
The terminal count signal becomes active for one clock during the last DMA transfer cycle.
6.13 Forcible
Termination
In addition to the forcible interruption operation by means of NMI input, DMA transfer can be forcibly ter-
minated by the INITn bit of the DCHCn register (n = 0 to 3).
Remark:
The next condition can be set even during DMA transfer because the DSAn, DDAn, and
DBCn registers are buffered registers. However, the setting to the DADCn register is invalid
(refer to 6.9 Next Address Setting Function and 6.3.4 DMA addressing control regis-
ters 0 to 3 (DADC0 to DADC3)).
6.14 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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