If AES_MR.LOD = 1

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

The user must first wait for the DMA buffer transfer complete flag, then for the flag DATRDY to rise to ensure that the encryption/decryption is completed (see the following figure).

The DMA receive channel must not be used. Prior to reading the CBC-MAC result, AES_MR.SMOD must be written to ‘0’. To restart a CBC-MAC on a new buffer, AES_MR.SMOD must be written to ‘2’.

The output data are only available on AES_ODATARx.

Figure 7-5. DMA Transfer with AES_MR.LOD = 1

The following table summarizes the different cases.

Table 7-1. Last Output Data Mode Behavior versus Start Modes
Sequence	Manual and Auto Modes		DMA Transfer
Sequence	AES_MR.LOD = 0	AES_MR.LOD = 1	AES_MR.LOD = 0	AES_MR.LOD = 1
DATRDY Flag Clearing Condition⁽¹⁾	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 Buffer transfer complete flags (channel m and channel n)	DMA buffer transfer complete flag, then AES DATRDY flag
Encrypted/Decrypted Data Result Location	In AES_ODATARx	In AES_ODATARx	At the address specified in the Channel Buffer Transfer Descriptor	In AES_ODATARx

Note:

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

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