The extended firmware patches fluidd.cfg to add a hook system for PRINT_START, PRINT_END, and CANCEL_PRINT. Features and custom macros can react to print lifecycle events without modifying any stock macro.
At the end of PRINT_START, and at the start of PRINT_END and CANCEL_PRINT, the macro iterates printer.configfile.config and calls every gcode_macro whose name matches the relevant prefix:
| Event | Hook prefix | Called |
|---|---|---|
PRINT_START |
_PRINT_START_ |
after the original |
PRINT_END |
_PRINT_END_ |
before the original |
CANCEL_PRINT |
_CANCEL_PRINT_ |
before the original |
PRINT_END and CANCEL_PRINT hooks run first so features can do cleanup (e.g. update spool state) before the printer parks and turns off heaters.
Create a gcode_macro with the matching prefix inside any .cfg file loaded by Klipper. Placing it in extended/klipper/ is the recommended location.
[gcode_macro _PRINT_START_MY_FEATURE]
gcode:
RESPOND TYPE=echo MSG="my feature: print started"
[gcode_macro _PRINT_END_MY_FEATURE]
gcode:
RESPOND TYPE=echo MSG="my feature: print ended"
[gcode_macro _CANCEL_PRINT_MY_FEATURE]
gcode:
RESPOND TYPE=echo MSG="my feature: print cancelled"
No existing macro needs to be modified. Hooks are discovered at runtime from the live config.
Hooks are called in the order Klipper processed the config sections, which follows the alphabetical file order within each included directory. If ordering between hooks matters, use a numeric prefix in the macro name (e.g. _PRINT_END_10_SPOOLMAN, _PRINT_END_20_NOTIFY).
Hooks receive no parameters. If a hook needs slicer-supplied values (e.g. bed temperature), read them from printer.configfile.settings or via a shared gcode_macro variable.
Turn the cavity LED on when a print starts and off when it ends or is cancelled.
[gcode_macro _PRINT_START_CAVITY_LED]
gcode:
SET_LED LED=cavity_led WHITE=1.0
[gcode_macro _PRINT_END_CAVITY_LED]
gcode:
SET_LED LED=cavity_led WHITE=0
[gcode_macro _CANCEL_PRINT_CAVITY_LED]
gcode:
SET_LED LED=cavity_led WHITE=0