The TreadleRepl is a character based debug facility for firrtl circuits. It has a host of features that let a user manual peek and poke values, advance the clock and set monitoring in a number of ways.


The TreadleRepl can be launched from a terminal session by running the ./ script. To launch it for a local firrtl file myfile.fir use:

./ -frfs myfile.fir

Faster launching

The above script uses sbt to run and that can be a bit slow to start up. You can build a executable jar for the TreadleRepl by executing

sbt assembly

This will create an executable jar in the utils/bin directory. In that directory there is a script treadle that will launch that jar. You can copy both the jar and script to your own local bin or make symbolic links to it.

Command line options

There are many command line options available to see them all, add –help to the command line.

The Repl commands

To get started at the prompt type the help command to see what the other commands are.

Currently the commands are

command description
load fileName load/replace the current firrtl file
script fileName load a script from a text file
run [linesToRun|all|list|reset] run loaded script
vcd [load|run|list|test|help] control vcd input file
record-vcd [<fileName<]|[done] treadle.vcd loaded script
symbol regex show symbol information
watch [+|-] regex [regex …] watch (+) or unwatch (-) signals
poke inputSymbol value set an input port to the given integer value
force symbol value hold a wire to value (use value clear to clear forced wire)
rpoke regex value poke value into portSymbols that match regex
peek symbol [offset] show the current value of the signal
rpeek regex show the current value of symbols matching the regex
randomize randomize all symbols except reset)
reset [numberOfSteps] assert reset (if present) for numberOfSteps (default 1)
reset [b|d|x|h] Set the output radix to binary, decimal, or hex
step [numberOfSteps] cycle the clock numberOfSteps (default 1) times, and show state
waitfor symbol value [maxNumberOfSteps] wait for particular value (default 1) of symbol, up to maxNumberOfSteps (default 100)
depend [childrenOf|parentsOf] signal [depth] | depend compare symbol1 symbol2 show dependency relationship to symbol or between two symbols
show [state|inputs|outputs|clocks|firrtl|lofirrtl] show useful things
display symbol[, symbol, …] show computation of symbols
info show information about the circuit
walltime [advance] show current wall time, or advance it
verbose [true|false|toggle] set evaluator verbose mode (default toggle) during dependency evaluation
snapshot save state of engine
restore restore state of engine from snapshot file
waves symbolName … generate wavedrom json for viewing waveforms
history [pattern] show command history, with optional regex pattern
help [markdown] show repl commands (in markdown format if desired)
quit exit the engine