Datasheet

Value Description
1
The DATRDY flag is cleared when at least one of the Input Data Registers is written.
No more Output Data Register reads are necessary between consecutive encryptions/decryptions (see
Last Output Data Mode).
Bits 14:12 – OPMOD[2:0] Operating Mode
For CBC-MAC operating mode, set OPMOD to CBC and LOD to 1.
Value Name Description
0
ECB ECB: Electronic Codebook mode
1
CBC CBC: Cipher Block Chaining mode
2
OFB OFB: Output Feedback mode
3
CFB CFB: Cipher Feedback mode
4
CTR CTR: Counter mode (16-bit internal counter)
5
GCM GCM: Galois/Counter mode
Bits 11:10 – KEYSIZE[1:0] Key Size
Value Name Description
0
AES128 AES Key Size is 128 bits
1
AES192 AES Key Size is 192 bits
2
AES256 AES Key Size is 256 bits
Bits 9:8 – SMOD[1:0] Start Mode
If a
DMA transfer is used, configure SMOD to 2. See DMA Mode for more details.
Value Name Description
0
MANUAL_START Manual Mode
1
AUTO_START Auto Mode
2
IDATAR0_START AES_IDATAR0 access only Auto Mode (DMA)
Bits 7:4 – PROCDLY[3:0] Processing Delay
Processing T
ime = 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.
Bit 3 – DUALBUFF Dual Input Buffer
Value Name Description
0
INACTIVE AES_IDATARx cannot be written during processing of previous block.
1
ACTIVE AES_IDATARx can be written during processing of previous block when SMOD = 2. It
speeds up the overall runtime of large files.
Bit 1 – GTAGEN GCM Automatic T
ag Generation Enable
Value Description
0
Automatic GCM Tag generation disabled.
1
Automatic GCM Tag generation enabled.
Bit 0 – CIPHER Processing Mode
Value Description
0
Decrypts data.
1
Encrypts data.
SAM E70/S70/V70/V71 Family
Advanced Encryption Standard (AES)
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1803