SPRUIM2H May 2020 – October 2023 AM2431 , AM2432 , AM2434 , AM6411 , AM6412 , AM6421 , AM6422 , AM6441 , AM6442
If DMA controller is available in a system the CRC module can also operate in semi-CPU mode. This means that CPU can still make use of the DMA to perform data patterns transfer to CRC controller in the background. The difference between semi-CPU mode and AUTO mode is that CRC controller does not automatically perform the signature verification. CRC controllers generates a compression complete interrupt to CPU when the one sector of data patterns are compressed. CPU needs to perform the signature verification itself.
A memory area with 2 Mbytes is to be verified with the help of the CPU. CRC operation is to be performed every 1 Kbyte. Since there are 2 Mbytes (256 K doublewords) of memory to be check and we want to perform a CRC every 1 Kbytes (128 doublewords) and therefore there must be 2048 pre-recorded CRC values. In Semi-CPU mode, the MCRC_CRC_REGL1/H1 is not updated and contains indeterminate data.