SPRUIY4B February 2023 – May 2024 TMS320F2800152-Q1 , TMS320F2800153-Q1 , TMS320F2800154-Q1 , TMS320F2800155 , TMS320F2800155-Q1 , TMS320F2800156-Q1 , TMS320F2800157 , TMS320F2800157-Q1
To implement lockstep scheme, a comparator block is needed. The comparator block compares the delayed version of relevant outputs of the primary module and the equivalent outputs of the secondary (redundant) module. This provides immunity towards the common cause failures like loss of power, clock failures, etc.
The LCM has two instantiations of the comparator block to provide redundancy of the comparator block. This enables availability of one comparator block during self-test of the other comparator block and also provides additional failure protection capability for the comparator logic.
Although the lockstep secondary (redundant) module is enabled upon startup, lockstep comparison must be enabled in software.
Once lockstep compare is enabled in software, the comparison is performed continuously every cycle, from the immediate next cycle. Any difference between the primary and secondary modules generates an error signal from the LCM to the SoC. The corresponding register bit is also set (LCM_STATUS.CMP_FAIL).
CPU reset (or any higher-level resets) disables the lockstep comparators, requiring re-enabling of the comparator in software.