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Chapter 7
DMA Functions (DMA Controller)
Preliminary User’s Manual U15839EE1V0UM00
7.2.6 DMA disable status register (DDIS)
This register holds the contents of the ENn bit of the DCHCn register during NMI input.
This register is read-only in 8-bit or 1-bit units.
Figure 7-8:
DMA Disable Status Register (DDIS)
Remark:
n = 0 to 3
7.2.7 DMA restart register (DRST)
This register is used to restart DMA transfer that has been forcibly interrupted by a non-maskable inter-
rupt (NMI). The ENn bit of this register and the ENn bit of the DCHCn register are linked to each other.
Following forcible interrupt by NMI input, the DMA channel that was interrupted is confirmed from the
contents of the DDIS register, and DMA transfer is restarted by setting the ENn bit of the corresponding
channel to 1.
This register can be read/written in 8-bit or 1-bit units.
Figure 7-9:
DMA Restart Register (DRST)
Remark:
n = 0 to 3
7
6
5
4
3
2
1
0
Address
Initial
value
DDIS
0
0
0
0
CH3
CH2
CH1
CH0
FFFFF0F0H
00H
Bit Position
Bit Name
Function
3 to 0
CH3 to
CH0
Reflects the contents of the ENn bit of the DCHCn register during NMI input. The con-
tents of this register are held until the next NMI input or until the system is reset.
7
6
5
4
3
2
1
0
Address
Initial
value
DRST
0
0
0
0
EN3
EN2
EN1
EN0
FFFFF0F2H
00H
Bit Position
Bit Name
Function
3 to 0
EN3 to
EN0
Specifies whether DMA transfer through DMA channel n is to be enabled or disabled.
This bit is cleared to 0 when DMA transfer is completed in accordance with the termi-
nal count output.
It is also cleared to 0 when DMA transfer is forcibly terminated by setting the INITn bit
to 1 or by NMI input.
0: DMA transfer disabled
1: DMA transfer enabled
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