13.4.14.1 Real-Time Pattern Matching

The MATCHEN bit (DMAxCH[2]) is used to enable the feature per selected channel; see DMAxCH. Once enabled, the contents of DMABUF[31:0] and DMAxPAT[31:0] are subjected to the corresponding DMAxMSK[31:0] bits’ value and compared against each other. When a match is detected, the DMA Controller proceeds to invoke its channel interrupt output while setting the MATCH bit (DMAxSTAT[1]) accordingly. Note that the DMA operation continues until completion, unaffected by the real-time matching. Upon interrupt detection by the CPU, the user’s software is expected to start processing the incoming data until it comes across the pattern.

Note:
  1. It is up to the user’s software to promptly clear the MATCH bit (DMAxSTAT[1]) in order to prevent an overrun-like condition, where multiple matches occur with no CPU response.
  2. The pattern match feature does not take SIZE[1:0] into account, so it is left to the user’s software to set the mask accordingly.
Figure 13-9. Pattern Match