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Chapter 15
DMA Functions (DMA Controller)
User’s Manual U16702EE3V2UD00
(8)
DMA trigger factor register (DTFRn)
The DTFRn register selects the DMA transfer start trigger through interrupt. The interrupt source
selected in this register serves as trigger to start the DMA transfer.
The register can be read or written in 8-bit or 1-bit units. However, only bit 7 (DFn) can be read/
written in 1-bit units.
Initial value is 00H by reset.
Figure 15-11:
DMA Trigger Factor Register (DTFRn) Format
Cautions: 1. Set the IFCn5 to IFCn0 bits at the following timing when DMA transfer is disabled
(DCHCn.Enn bit = 0).
•
Period from after reset to start of first DMA transfer
•
Period from after channel initialization by DCHCn.INITn bit to start of DMA
transfer
•
Period from after completion of DMA transfer (DCHCn.TCn bit = 1) to start of
the next DMA transfer
2. Be sure to follow the steps below when changing the DTFRn register settings.
•
When the values to be set to bits IFCn5 to IFCn0 are not set to bits IFCm5 to
IFCm0 of another channel (n = 0 to 3, m = 0 to 3, n
≠
m)
<1> Stop the DMAn operation of the channel to be rewritten
(DCHCn.Enn bit = 0).
<2> Change the DTFRn register settings. (Be sure to set DFn bit = 0 and
change the settings in the 8-bit manipulation.)
<3> Confirm that DFn bit = 0. (Stop the interrupt generation source
operation beforehand.)
<4> Enable the DMAn operation (Enn bit = 1).
•
When the values to be set to bits IFCn5 to IFCn0 are set to bits IFCm5 to
IFCm0 of another channel (n = 0 to 3, m = 0 to 3, n
≠
m)
<1> Stop the DMAn operation of the channel to be rewritten
(DCHCn.Enn bit = 0).
<2> Stop the DMAm operation of the channel where the same values are set
to bits IFCm5 to IFCm0 as the values to be used to rewrite bits IFCn5 to
IFCn0 (DCHCm.Emm bit = 0).
<3> Change the DTFRn register settings. (Be sure to set DFn bit = 0 and
change the settings in the 8-bit manipulation.)
<4> Confirm that bits DFn and DFm = 0. (Stop the interrupt generation
source operation beforehand.)
<5> Enable the DMAn operation (bits Enn and Emm = 1).
DTFR0=FFFFFF40H, DTFR1=FFFFFF42H, DTFR2=FFFFFF44H,
DTFR3=FFFFFF46H, DTFR4=FFFFFF48H, DTFR5=FFFFFF4AH
Symbol
7
6
5
4
3
2
1
0
Address
After reset
DTFRn
DFn
0
IFCn5
IFCn4
IFCn3
IFCn2
IFCn1
IFCn0
00H
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
DF
DMA transfer request flag
0
No DMA transfer request
1
DMA transfer request
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