
54
XMEGA A [MANUAL]
8077I–AVR–11/2012
5.13
Register Description – DMA Controller
5.13.1 CTRL – Control register
Bit 7 – ENABLE: Enable
Setting this bit enables the DMA controller. If the DMA controller is enabled and this bit is written to zero, the ENABLE bit
is not cleared before the internal transfer buffer is empty, and the DMA data transfer is aborted.
Bit 6 – RESET: Software Reset
Writing a one to RESET will be ignored as long as DMA is enabled (ENABLE = 1). This bit can be set only when the DMA
controller is disabled (ENABLE = 0).
Bit 5:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
Bit 3:2 – DBUFMODE[1:0]: Double Buffer Mode
These bits enable the double buffer on the different channels according to
Table 5-1.Table 5-1.
DMA double buffer settings.
Bit 1:0 – PRIMODE[1:0]: Channel Priority Mode
These bits determine the internal channel priority according to
Table 5-2Table 5-2.
DMA channel priority settings.
Bit
765
432
10
+0x00
ENABLE
RESET
–
DBUFMODE[1:0]
PRIMODE[1:0]
Read/Write
R/W
R
R/W
Initial Value
000
00
DBUFMODE[1:0]
Group Configuration
Description
00
DISABLED
No double buffer enabled
01
CH01
Double buffer enabled on channel0/1
10
CH23
Double buffer enabled on channel2/3
11
CH01CH23
Double buffer enabled on channel0/1 and channel2/3
PRIMODE[1:0]
Group Configuration
Description
00
RR0123
Round robin
01
CH0RR123
Channel0 > Round robin (channel 1, 2 and 3)
10
CH01RR23
Channel0 > Channel1 > Round robin (channel 2 and 3)
11
CH0123
Channel0 > Channel1 > Channel2 > Channel3