SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
To facilitate software self-test, MISRs are instantiated on address and data buses at key points in the system, such as ARP32 interfaces and the interconnect-WBUF interface. ARP32 is covered because it is the key control engine. WBUF coverage is provided as a convenient central destination that is used to indirectly provide coverage for a majority of EVE logic.
The MISRs monitor the address and data buses and calculate a signature based on the address or data pattern on a valid address or data phases. The signature registers reset to 0. A different speed value can be manually written through software to each signature register: MISR0_A, MISR0_D, MISR1_A, MISR1_D, and MISR2_Dk. Based on a known memory access data pattern, the MISR signature can be predicted or calculated and used as a reference for subsequent tests that occur at boot time or during runtime in a safety critical application.
The MISR calculation is a shift-register/XOR tree calculation using classical CRC algorithms.
The MISR calculation is initiated by setting the MISR_CTL[2:0] ENABLE bit field:
The MISR_CLEAR[2:0] CLEAR register clears the MISR 0 and MISR 1 calculations for the corresponding path.
Table 8-24 describes the location and width of the various MISRs in the system and is shown as thick blue lines in the block diagram in Figure 8-1.