Xilinx MicroBlaze Reference Manual page 116

In this system two redundant MicroBlaze processors run in lockstep. A comparator is used
to signal an error when a mis-match is detected on the outputs of the two processors. Any
error immediately causes both processors to halt, preventing further error propagation.
The redundant MicroBlaze processors are functionally identical, except for debug logic and
associated signals.The outputs from the master MicroBlaze core drive the peripherals in the
system. The slave MicroBlaze core only has inputs connected; all outputs are left open.
The system contains the basic building block for designing a complete fault tolerant
application, where one or more additional blocks must be added to provide redundancy.
This use case is illustrated in
DLMB
BRAM Controller
BRAM
ILMB
BRAM Controller
MicroBlaze
Debug Module
MicroBlaze Processor Reference Guide
UG984 (v2016.2) June 8, 2016
UG984 (v2016.1) April 6, 2016
Figure 2-42.
C_LOCKSTEP_SLAVE = 0
MicroBlaze
Master
Debug
Debug
MicroBlaze
Inputs
Slave
C_LOCKSTEP_SLAVE = 1
Figure 2-42: Lockstep Error Detection Application
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Chapter 2: MicroBlaze Architecture
Error Reset
Outputs
Inputs
Lockstep_Out
Comparator
Lockstep_Out
Inputs
Inputs
I/O Interfaces
External Memory
Interfaces
116
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