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Atmel AVR XMEGA AU series User Manual

Atmel AVR XMEGA AU series
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329
8331B–AVR–03/12
Atmel AVR XMEGA AU
26.3 Operation
The data source for the CRC module must be selected in software as either flash memory, the
DMA channels, or the I/O interface. The CRC module then takes data input from the selected
source and generates a checksum based on these data. The checksum is available in the
CHECKSUM registers in the CRC module. When CRC-32 polynomial is used, the final check-
sum read is bit reversed and complemented (see Figure 26-1).
For the I/O interface or DMA controller, which CRC polynomial is used is software selectable,
but the default setting is CRC-16. CRC-32 is automatically used if Flash Memory is selected as
the source. The CRC module operates on bytes only.
Figure 26-1. CRC generator block diagram.
26.4 CRC on Flash memory
A CRC-32 calculation can be performed on the entire flash memory, on only the application sec-
tion, on only the boot section, or on a software selectable range of the flash memory. Other than
selecting the flash as the source, all further control and setup are done from the NVM controller.
This means that the NVM controller configures the memory range to perform the CRC on, and
the CRC is started using NVM commands. Once completed, the result is available in the check-
sum registers in the CRC module. For further details on setting up and performing CRC on flash
memory, refer to ”Memory Programming” on page 431.
DATAIN
CTRL
Flash
Memory
DMA
Controller
CRC-16
CRC-32
CHECKSUM
bit-reverse +
complement
16
8
8
32
Checksum read
crc32

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Atmel AVR XMEGA AU series Specifications

General IconGeneral
BrandAtmel
ModelAVR XMEGA AU series
CategoryMicrocontrollers
LanguageEnglish

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