SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
There are two DMA channels associated with each CRC channel when in AUTO mode. One DMA channel is setup to transfer data patterns from the source memory to the PSA Signature Register (MCRC_PSA_SIGREGL1-4). The second DMA channel is setup to transfer the pre-determined signature to the CRC Value Register (MCRC_CRC_REGL1-4 ). The trigger source for the first DMA channel can be either by hardware or by software. As illustrated in Figure 12-2982, a timer can be used to trigger a DMA request to initiate transfer from the source memory system to PSA Signature Register. In AUTO mode, MCRC Controller also generates DMA request after one sector of data patterns is compressed to initiate transfer of the next CRC value corresponding to the next sector of memory. Thus a new CRC value is always updated in the CRC Value Register (MCRC_CRC_REGL1-4)by DMA synchronized to each sector of memory.
A block of memory system is usually divided into many sectors. All sectors are the same size. The sector size is programmed in the MCRC_CRC_PCOUNT_REG1-4 and the number of sectors in one block is programmed in the MCRC_CRC_SCOUNT_REG1-4 of the respective channel. MCRC_CRC_PCOUNT_REG1-4 multiplies MCRC_CRC_SCOUNT_REG1-4 and multiplies transfer size of each data pattern should give the total block size in number of bytes.
The total size of the memory system to be examined is also programmed in the respective transfer count register inside DMA module. The DMA transfer count register is divided into two parts. They are element count and frame count. Note that a hardware DMA request can be programmed to trigger either one frame or one entire block transfer. In Figure 12-2982, a hardware DMA request from a timer is used as a trigger source to initiate DMA transfer. If all four CRC channels are active in AUTO mode then a total of four DMA requests would be generated by MCRC Controller.