The Data OUT (DOUT) DMA engine transfers data from the CRYPTOCELL subsystem and its various cryptographic engines.
The DOUT DMA engine provides a comprehensive interface to facilitate the transfer of data from the cryptographic engines to the CPU or memory. It includes a variety of registers that control direct data buffering, DMA operations, and data flow management.
Maximum DMA transaction size is limited to 216-1 bytes. If a DMA transaction is configured with a payload size above the maximum DMA transaction size limit, the DMA engine must be reset before being functional again using register DOUT_SW_RESET.
The flow demonstrated in Cryptographic flow shows how the DOUT DMA engine is configured to output data from the AES engine using registers DST_MEM_ADDR and DST_MEM_SIZE to define the output source address and number of output bytes, respectively.