Atmel Evaluation Kit for the SAM4E Series of Flash Microcontrollers ATSAM4E-EK ATSAM4E-EK Scheda Tecnica

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SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

This mode is recommended to process AES CBC-MAC operating mode.

The user must first wait for the DMA flag (BTC = Buffer Transfer Complete) to be raised, then for DATRDY to
ensure that the encryption/decryption is completed (see 

In this case, no receive buffers are required.

The output data are only available on the AES_ODATARx.

 summarizes the different cases.

Note:

1. Depending on the mode, there are other ways of clearing the DATRDY flag. See 

Warning: In DMA mode, reading to the AES_ODATARx before the last data transfer may lead to unpredictable results.

Enable DMA Channels associated to AES_IDATARx and AES_ODATARx

Multiple Encryption or Decryption Processes

BTC /channel 1

BTC /channel 0

Message fully processed 
(cipher or decipher) last 
block can be read

Write accesses into AES_IDATARx 

Read accesses into AES_ODATARx 

DATRDY

Enable DMA Channels associated with TDES_IDATARx and TDES_ODATARx registers

Multiple Encryption or Decryption Processes

BTC / channel 0

Message fully processed 
(cipher or decipher) 
MAC result  can be read

Write accesses into AES_IDATARx 

Message fully transferred

DATRDY Flag 

Clearing Condition

At least one 
AES_ODATAR must be 
read

At least one 
AES_IDATAR must be 
written

Not used

Managed by the DMA

End of 

Encryption/Decryption 

Notification

DATRDY

DATRDY

2 DMA flags (BTC[n/m])

DMA flag (BTC[n]) then 
DATRDY

Encrypted/Decrypted 

Data Result Location

In the AES_ODATARx

In the AES_ODATARx

At the address specified 
in the Channel Buffer 
Transfer Descriptor

In the AES_ODATARx