Datasheet

637
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
31.6.2 AES Mode Register
Name: AES_MR
Address: 0x40004004
Access: Read/Write
 CIPHER: Processing Mode
0: Decrypts data.
1: Encrypts data.
 DUALBUFF: Dual Input Buffer
 PROCDLY: Processing Delay
Processing Time = N × (PROCDLY + 1)
where
N = 10 when KEYSIZE = 0
N = 12 when KEYSIZE = 1
N = 14 when KEYSIZE = 2
The Processing Time represents the number of clock cycles that the AES needs in order to perform one
encryption/decryption.
Note: The best performance is achieved with PROCDLY equal to 0.
 SMOD: Start Mode
Values which are not listed in the table must be considered as “reserved”.
If a DMA transfer is used, 0x2 must be configured. Refer to Section 31.4.3.3 “DMA Mode” for more details.
31 302928 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
CKEY – CFBS
15 14 13 12 11 10 9 8
LOD OPMOD KEYSIZE SMOD
76543 210
PROCDLY DUALBUFF – – CIPHER
Value Name Description
0x0 INACTIVE AES_IDATARx cannot be written during processing of previous block.
0x1 ACTIVE
AES_IDATARx can be written during processing of previous block when SMOD = 0x2. It speeds
up the overall runtime of large files.
Value Name Description
0x0
MANUAL_STAR
T
Manual Mode
0x1 AUTO_START Auto Mode
0x2 IDATAR0_START AES_IDATAR0 access only Auto Mode