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CHAPTER 6 DMA FUNCTIONS (DMA CONTROLLER)
139
User’s Manual U14492EJ5V0UD
6.3.8 DMA trigger factor registers 0 to 3 (DTFR0 to DTFR3)
These 8-bit registers are used to control the DMA transfer start trigger through interrupt requests from on-chip
peripheral I/O.
The interrupt requests set with these registers serve as DMA transfer start factors.
These registers can be read/written in 8-bit units. Only bit 7 (DFn) can be read/written in 1-bit units, and bits 5 to 0
(IFCn5 to IFCn0) can be read/written in 8-bit units (n = 0 to 3).
Be sure to set bit 6 to 0. If it is set to 1, the operation is not guaranteed.
Cautions 1. Be sure to stop DMA operation before making changes to DTFRn register settings.
2. An interrupt request input in a standby mode (IDLE or software STOP mode) cannot be used
as a DMA transfer start factor except for INTP0 to INTP6 and INTP20 to INTP25 (when the
noise elimination by analog filter is selected).
3. If the start factor for DMA transfer is changed using the IFCn5 to IFCn0 bits, be sure to clear
(0) the DFn bit with the instruction immediately after the change.
(1/2)
<7>
DTFR0
6
5
4
3
2
1
0
DF0
0
IFC05
IFC04
IFC03
IFC02
IFC01
IFC00
Address
FFFFF810H
Initial value
00H
<7>
DTFR1
6
5
4
3
2
1
0
DF1
0
IFC15
IFC14
IFC13
IFC12
IFC11
IFC10
FFFFF812H
00H
<7>
DTFR2
6
5
4
3
2
1
0
DF2
0
IFC25
IFC24
IFC23
IFC22
IFC21
IFC20
FFFFF814H
00H
<7>
DTFR3
6
5
4
3
2
1
0
DF3
0
IFC35
IFC34
IFC33
IFC32
IFC31
IFC30
FFFFF816H
00H
Bit position
Bit name
Function
7
DFn
This is a DMA transfer request flag.
Only 0 can be written to this flag.
0: No DMA transfer request
1: DMA transfer request
If an interrupt that causes DMA transfer occurs while DMA transfer is disabled (including if
it has been suspended by an NMI or forcibly terminated by software), and if this DMA
transfer request must be cleared, stop the operation causing the interrupt (e.g., disable
reception if serial reception is in progress), and then clear the DFn bit. If it is clear in the
application that the interrupt will not occur again until DMA transfer is resumed next, it is
not necessary to stop the operation causing the interrupt.
Sets the interrupt source that serves as the DMA transfer start factor.
IFCn5
IFCn4
IFCn3
IFCn2
0
0
0
0
IFCn1
0
IFCn0
0
Interrupt Source
DMA request from on-chip
peripheral I/O disabled
INTP0
INTP1
INTP2
INTP3
INTP4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
1
0
0
1
0
1
0
1
5 to 0
IFCn5 to
IFCn0
Remark
n = 0 to 3