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R01UH0336EJ0102 Rev.1.02
Page 201 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 5 DMA Module
Transfer mode
• Single transfer mode (when a hardware DNA transfer request is generated)
When a hardware DMA transfer request is generated, the controller
acquires bus mastership and then releases the bus after one cycle of
transfer. If another hardware DMA transfer request is subsequently
generated, transfer is executed again. This operation is repeated until
transfer has been executed the number of times specified in the transfer
count register (DTCn).
• Single-step transfer mode (when a software DMA transfer request is
generated)
When a software DMA transfer request is generated, the bus mastership is
acquired, and the bus is released per unit transfer. Once a software DMA
transfer request has been acknowledged, this operation is repeated until
unit transfers have been executed the number of times specified by the
transfer count register (DTCn).
Transfer address
control
Incrementation
Decrementation
Fixed
Transfer error
support
When the data from the transfer source contains an error or an error occurs at
the transfer destination, DMA transfer is stopped and a SysError exception is
issued to notify the CPU.
DMA transfer
request
A hardware DMA transfer request or software DMA transfer request can be
selected for each channel (by setting the DTRSn register). A software DMA
transfer request can be set by software (by setting the DTS register). This
register also has a status bit (DTS register) to indicate when a hardware DMA
transfer request has been generated.
Interrupt output
upon a match of
transfer count
This function has a transfer count compare register (DTCCn) for each channel
and outputs an interrupt signal (INTDMACT7 to INTDMACT0) when the value
in this register matches that in the transfer count register (DTCn) for any
channel.
Interrupt output on
completion of
transfer
This function outputs a transfer completion interrupt signal (INTDMA7 to
INTDMA0) when DMA unit transfer on any channel has been completed the
number of times specified in the transfer count register (DTCn).
Next address
setting
Setting of the next address is handled by equipping each channel with two sets
of registers: one for setting the transfer address and transfer count (current
transfer registers) of the DMA transfer currently being executed, and the other
for setting the transfer address and transfer count (next transfer registers) for
the next DMA transfer, i.e. that will follow completion of the DMA transfer that
is currently in progress. The registers also have a bit for setting whether to
copy values from the “next” to the “current” registers on completion of DMA
transfer.
DMA transfer
suspension
This function supports DMA transfer suspension by software.
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