Time-based Redundancy Modules

[Lynx005F]

Depends on Voter Macros (#25)

Various modules to make any (pipelined) combinatorial processes redundant in a time-based fashion e.g. sending the same operation for multiple cycles and comparing results. Redundancy can be switched off at runtime.

• time-based TMR (error correction)
• time-based DMR (error detection)
• Modules to retry operations that failed (can be used with time-based DMR or parallel DMR)
  • Fast variant resulting in out-of-orderness
  • Slower variant keeping operations in order
• Controller module that can safely switch into and out off time-based redundant modes
• Lockable Round-Robin Arbitrator so out-of-order Pipelines can be used with time-based redundancy

Testing

The integrated testbenches include:

• The modules are tested for throughput, correct handshake behaviour under stalls.
• Error injection via XORs are done in betwen the modules to check the following behaviour:
  • Correct output under handshake failure (single bit flip in a single cycle)
  • Correct output under ID failure (any number of bitflips in a single cycle)
  • Corect output under Datapath failure (any number of bitflips in a single cycle)

[Lynx005F]

I am checking a potential issue with the lockable rr arbiter.

[Lynx005F]

The issue with the Lockable RR-Arbiter turned out to be because of an incorrect parameterization when instantiating it. I added an assertio to cover this case.