Fujitsu FR81S User Manual
CHAPTER 8: DMA CONTROLLER (DMAC)
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : DMA CONTROLLER (DMAC)
FUJITSU SEMICONDUCTOR CONFIDENTIAL
43
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Transfer size
: DCCRn:TS = 11
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Demand transfer mode by software request : DCCRn:RS = 00 and DCCRn:TM = 11
Interrupt request
The DMAC can issue an interrupt request at normal termination of data transfer, at abnormal termination of
data transfer, or at transfer suspension by a transfer stop request. When issuing an interrupt request, set the
interrupt controller as well.
Use the DMA channel status register (DCSRn) to check the interrupt request cause or to clear the interrupt
request.
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Interrupt request at normal termination
If the normal termination interrupt of a channel is enabled (DCCRn:NIE=1), the DMAC issues the
interrupt request at the normal termination.
However, the DCSRn:NC bit of the corresponding channel must be set regardless of the normal
termination interrupt setting (DCCRn:NIE).
Clear the interrupt request by clearing the DCSRn:NC bit of the corresponding channel.
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Interrupt request at abnormal termination
If the abnormal termination interrupt of a channel is enabled (DCCRn:AIE=1), the DMAC issues the
interrupt request at the abnormal termination. However, the DCSRn:AC bit of the corresponding
channel is set regardless of the abnormal termination interrupt (DCCRn:AIE) setting.
Clear the interrupt request by clearing the DCSRn:AC bit of the corresponding channel.
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A transfer suspension interrupt request by a transfer stop request
If the transfer suspension interrupt of a channel is enabled (DCCRn:AIE=1), the DMAC issues the
interrupt request if data transfer is suspended by a transfer stop request. However, the DCSRn:SP bit of
the corresponding channel is set regardless of the transfer suspension interrupt (DCCRn:SIE) settings.
Clear the interrupt request by clearing the DCSRn:SP bit of the corresponding channel.
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DMA transfer suppressing
The DMA transfer is suppressed due to the following causes.
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A DMA transfer suppress request from DSU/OCD (for debugging)
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NMI
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Peripheral interrupt
The DMA transfer is suppressed in units of blocks. If data transfer is suppressed, new data transfer does not
start. Data transfer is stopped. The settings to restart data transfer vary depending on the DMA transfer
suppress causes.
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DMA transfer suppressing request from DSU/OCD (for debugging)
When the DMA transfer suppressing request by DSU/OCD is asserted, a new transfer does not start and a
current transfer stops with the block unit. The acknowledge is not returned to the DMA transfer
suppressing from DSU/OCD.
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DMA transfer suppressing by NMI
If the NMIH bit is set to "0", DMAC sets NMIH flag when user NMI occurs and suppresses DMA
transfer after the block unit transfer is done.
Write "0" in the NMIH flag when you restart transfer.
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DMA transfer suppressing by peripheral interrupt
If an interrupt having the level higher than the one specified in the DILVR register occurs, the DMA
transfer is suppressed after the current block has been transferred.
MB91520 Series
MN705-00010-1v0-E
342