61
8331B–AVR–03/12
Atmel AVR XMEGA AU
5.13.5
TEMPH – Temporary Register High
• Bit 7:0 – TEMP[15:8]: Temporary Register
This register is used when reading and writing 24-bit registers in the DMA controller. Byte 2 of
the 24-bit register is stored when it is written by the CPU. Byte 2 of the 24-bit register is stored
here when byte 1 is read by the CPU. This register can also be read and written from the user
software.
Reading and writing 24-bit registers requires special attention. For details, refer to
5.14
Register Description – DMA Channel
5.14.1
CTRLA – Control register A
• Bit 7 – ENABLE: Channel Enable
Setting this bit enables the DMA channel. This bit is automatically cleared when the transaction
is completed. If the DMA channel is enabled and this bit is written to zero, the CHEN bit is not
cleared until the internal transfer buffer is empty and the DMA transfer is aborted.
• Bit 6 – RESET: Software Reset
Setting this bit will reset the DMA channel. It can only be set when the DMA channel is disabled
(CHEN = 0). Writing a one to this bit will be gnored as long as the channel is enabled (CHEN=1).
This bit is automatically cleared when reset is completed.
• Bit 5 – REPEAT: Repeat Mode
Setting this bit enables the repeat mode. In repeat mode, this bit is cleared by hardware at the
beginning of the last block transfer. The REPCNT register should be configured before setting
the REPEAT bit.
• Bit 4 – TRFREQ: Transfer Request
Setting this bit requests a data transfer on the DMA channel. This bit is automatically cleared at
the beginning of the data transfer. Writing this bit does not have any effect unless the channel is
enabled.
• Bit 3 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write
this bit to zero when this register is written.
Bit
7
6
5
4
3
2
1
0
TEMP[15:8]
TEMPH
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
ENABLE
RESET
REPEAT
TRFREQ
–
SINGLE
BURSTLEN[1:0]
CTRLA
Read/Write
R/W
R/W
R/W
R/W
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0