393
8331B–AVR–03/12
Atmel AVR XMEGA AU
• Bit 1 – CH1DRE: Channel 1 Data Register Empty
This bit when set indicates that the data register for channel 1 is empty, meaning that a new con-
version value may be written. Writing to the data register when this bit is cleared will cause the
pending conversion data to be overwritten. This bit is directly used for DMA requests.
• Bit 0 – CH0DRE: Channel 0 Data register Empty
This bit when set indicates that the data register for channel 0 is empty, meaning that a new con-
version value may be written. Writing to the data register when this bit is cleared will cause the
pending conversion data to be overwritten. This bit is directly used for DMA requests.
29.10.6
CH0DATAH – Channel 0 Data Register High
These two channel data registers, CHnDATAH and CHnDATAL, are the high byte and low byte,
respectively, of the 12-bit CHnDATA value that is converted to a voltage on DAC channel n. By
default, the 12 bits are distributed with 8 bits in CHnDATAL and 4 bits in the four lsb positions of
CHnDATAH (right-adjusted).To select left-adjusted data, set the LEFTADJ bit in the CTRLC
register.
When left adjusted data is selected, it is possible to do 8-bit conversions by writing only to the
high byte of CHnDATA, i.e., CHnDATAH. The TEMP register should be initialized to zero if only
8-bit conversion mode is used.
29.10.6.1
Right-adjusted
• Bit 7:4 – 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 3:0 – CHDATA[11:8]: Conversion Data Register Channel 0, Four msbs
These bits are the four msbs of the 12-bit value to convert to channel 0 in right-adjusted mode.
29.10.6.2
Left-adjusted
• Bits 7:0 –- CHDATA[11:4]: Conversion Data Register Channel 0, Eight msbs
These bits are the eight msbs of the 12-bit value to convert to channel 0 in left-adjusted mode
Bit
7
6
5
4
3
2
1
0
Right-adjust
+0x19
–
–
–
–
CHDATA[11:8]
Left-adjust
CHDATA[11:4]
Right-adjust
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Left-adjust
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Right-adjust
Initial Value
0
0
0
0
0
0
0
0
Left-adjust
Initial Value
0
0
0
0
0
0
0
0