331
8331B–AVR–03/12
Atmel AVR XMEGA AU
26.7
Register Description
26.7.1
CTRL – Control register
• Bit 7:6 – RESET[1:0]: Reset
These bits are used to reset the CRC module, and they will always be read as zero. The CRC
registers will be reset one peripheral clock cycle after the RESET[1] bit is set.
• Bit 5 – CRC32: CRC-32 Enable
Setting this bit will enable CRC-32 instead of the default CRC-16. It cannot be changed while the
BUSY flag is set.
• Bit 4 – 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 3:0 – SOURCE[3:0]: Input Source
These bits select the input source for generating the CRC. The selected source is locked until
either the CRC generation is completed or the CRC module is reset. CRC generation complete
is generated and signaled from the selected source when used with the DMA controller or flash
memory.
Bit
7
6
5
4
3
2
1
0
+0x00
RESET[1:0]
CRC32
–
SOURCE[3:0]
CTRL
Read/Write
R/W
R/W
R/W
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Table 26-1.
CRC reset.
RESET[1:0]
Group configuration
Description
00
NO
No reset
01
—
Reserved
10
RESET0
Reset CRC with CHECKSUM to all zeros
11
RESET1
Reset CRC with CHECKSUM to all ones
Table 26-2.
CRC source select .
SOURCE[3:0]
Group configuration
Description
0000
DISABLE
CRC disabled
0001
IO
I/O interface
0010
FLASH
Flash
0011
—
Reserved for future use
0100
DMACH0
DMA controller channel 0
0101
DMACH1
DMA controller channel 1