Print Job State Machine

Happy Hare keeps track of the current print state in a similar way to the klipper print_stats module. It is subtly difference and can even work when streaming a job for Octoprint (altough some special precautions must be taken). The current state is available via the printer variable printer.mmu.print_job_state. This can be useful in your own custom gcode macros but also ensures that Happy Hare restores things like temperatures, stepper motor current and idle_timeout at the right time.

It is a good idea to familiarize yourself with this to aid debugging and state recovery even if you are not using in your own macros.

Job State Transitions

Important

Users printing from the "virtual SD-card" via Mainsail or Fluuid don't have any extras steps to take but if streaming a job (e.g. from Octoprint) the user is responsible to add _MMU_PRINT_START to their print_start macro or sequence and _MMU_PRINT_END to their end_print macro or sequence. The addition of those commands on "virtual sd-card print" will not cause harm but they are but are unecessary and will be ignored (hence the underscore naming). Also note that the print_start_detection setting can be used to disable the automatic behavior and act like a job streamed from Octoprint.

stateDiagram-v2
    initialized --> started: (print_start)
    note left of initialized: reset
    standby --> started: (print_start)
    note left of standby: idle_timeout
    ready --> started: (print_start)
    started --> printing
    printing --> complete: (print_complete))
    printing --> error: (print_error)
    printing --> cancelled: CANCEL_PRINT
    printing --> PAUSE: mmu error or MMU_PAUSE
    state PAUSE {
        direction LR
        pause_locked --> paused: (MMU_UNLOCK)
    }
    PAUSE --> printing: RESUME

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State machine transitions in detail...

MMU starts in initialized state. On printing it will briefly enter started (until _MMU_PRINT_START is complete) then transition to printing. On job completion (at end of _MMU_PRINT_END) or job error the state will transition to complete or error respectively. If the print is explicitly cancelled the CANCEL_PRINT interception transitions to cancelled. If idle_timeout is experience the state will transition back to standby. ready is a resting state similar to standby an just means that the printer is not yet idle.

While printing, if an mmu error occurs (or the user explicitly calls MMU_PAUSE) the state will transition to pause_locked. If the user is quick to respond (before extruder temp drops) the print can be resumed with RESUME command. The MMU_UNLOCK is optional and will restore temperatures allowing for direct MMU interaction and thus can be considered a half-step towards resuming (must still run RESUME to continue printing).

Note

• MMU_PAUSE outside of a print will have no effect unless MMU_PAUSE FORCE_IN_PRINT=1 is specified to mimick the behavior (like z-hop move and running PAUSE macro, etc).
• Directly calling PAUSE will stop the job but will have no effect on the MMU (i.e. it does not put the MMU into the pause_locked state, only MMU_PAUSE does that.
• When entering pause_locked Happy Hare will always remember the toolhead position and, if configured, perform a z-hop, but will also run the user PAUSE macro
• When RESUME is called the user RESUME macro will be called, finally followed by Happy Hare restoring the original toolhead position.
• Outside of a print the toolhead is never moved by Happy Hare (only user's PAUSE/RESUME macros).
• MMU_PRINT_END STATE=xxx if called directly can accept states complete|error|cancelled|standby|ready although typically would only be called with complete|error