
1077
6437E–ATARM–23-Apr-13
SAM9M11
OPMOD: Operation Mode
Values which are not listed in the table must be considered as “reserved”.
For CBC-MAC operating mode, please set OPMOD to CBC and LOD to 1.
LOD: Last Output Data Mode
0: No effect.
After each end of encryption/decryption, the output data is available either on the output data registers (Manual and Auto
modes) .
In Manual and Auto modes, the DATRDY flag is cleared when at least one of the Output Data registers is read.
1: The DATRDY flag is cleared when at least one of the Input Data Registers is written.
No more Output Data Register reads is necessary between consecutive encryptions/decryptions (see
“Last Output DataWarning: In DMA mode, reading to the Output Data registers before the last data encryption/decryption process may lead to
unpredictable results.
CFBS: Cipher Feedback Data Size
Values which are not listed in table must be considered as “reserved”.
CKEY: Countermeasure Key
This field should be written with the value 0xE to allow CTYPE field changes.
If the field is written with a different value, changes made through the CTYPE field will not be taken into account.
Note:
CKEY field is write-only.
CMTYP1: CounterMeasure Type 1
0 (NOPROT_EXTXKEY): Counter-Measure type 1 is disabled
1 (PROT_EXTKEY): Counter-Measure type 1 is enabled
Value
Name
Description
0x0
ECB
ECB: Electronic Code Book mode
0x1
CBC
CBC: Cipher Block Chaining mode
0x2
OFB
OFB: Output Feedback mode
0x3
CFB
CFB: Cipher Feedback mode
0x4
CTR
CTR: Counter mode (16-bit internal counter)
Value
Name
Description
0x0
SIZE_128BIT
128-bit
0x1
SIZE_64BIT
64-bit
0x2
SIZE_32BIT
32-bit
0x3
SIZE_16BIT
16-bit
0x4
SIZE_8BIT
8-bit