Menuconfig¶

The Happy Hare v4 Installer and Configurator is a dynamic, menuconfig based configuration management system designed to streamline both initial installation and ongoing maintenance of Happy Hare. It uses a structured, deterministic rules-based workflow that exposes only the parameters and capabilities relevant to your specific MMU hardware and enabled features.

Where appropriate, the installer applies recommended defaults and sensible settings across hardware definitions, GPIO assignments, and Happy Hare features. Options not applicable to your configuration are suppressed and omitted from the generated files in the config/mmu/base/ folder.

This rules‑driven approach simplifies setup, reduces configuration errors and frustration, and provides a clear, maintainable foundation for upgrading, managing, and enabling Happy Hare capabilities.

Design Goal¶

The intention is for users to manage most configuration settings through the interactive menuconfig installer (./install.sh -i), without needing to edit Happy Hare configuration files directly. The rules‑driven interface ensures that all configuration choices remain consistent with the selected MMU hardware and supported features.

Direct Modification of Configuration Files¶

Direct modification of Happy Hare configuration files remains possible when required, with installer options available to control merge and overwrite behavior to suit your preferred workflow. However, users are encouraged to rely primarily on the menuconfig installer, which may require unlearning older habits of editing configuration files directly.

All menuconfig selections are mastered and stored in the Happy-Hare/.mmu_config settings file, with per-unit .mmu_config_<name> files in multi-unit mode. Copies are maintained in printer_data/config/mmu/ so they are included in popular GitHub-based printer configuration backup mechanisms.

Navigation¶

Navigation is intuitive and the same as any other menuconfig based interface.

The top-down flow guides you through the process in a logical, step by step manner. Depending on the MMU and selections you make, additional sub-menus and settings will appear, enabling you to configure relevant settings for your MMU.

Any non modifiable settings that have been enabled based on your MMU design or due to prior selection will be preselected with
-*- and will include the (FIXED) designation e.g. -*- Has LEDs? (FIXED)

Config Warnings / Errors are highlighted for you to review and correct before saving and applying updates to your configuration.

Unit names¶

The Name menu separates the Klipper object name used in configuration from the Display name shown in the UI. The first unit defaults to unit0, but you can choose another name during installation. In multi-unit mode, edit object names in the shared MMU units list. See Naming an MMU unit.

Managing Configuration Changes¶

When the menuconfig installer is launched after your initial setup and configuration, you will be prompted to choose how it should apply and reconcile configuration changes with locally applied settings. The installer supports two modes, Merge/Refresh and Replace:

You are running an interactive install with existing menuconfig ('.mmu_config').

Read carefully, you have two options:

1) Merge/Refresh (select 1) (Default upgrade path)
   This KEEPS every change you made directly to your .cfg files. Before menuconfig opens,
   the simple settings your .cfg files hold are copied into menuconfig (you'll see the list
   and confirm), so menuconfig shows what you are actually running. Only the settings you
   then change in menuconfig are applied to your .cfg files, and new options are added.

2) Replace (select 2) (Recommended)
   This will OVERWRITE changes made directly to your .cfg files and create new default
   configuration based on choices made in menuconfig (which initializes to your previous config).
   This is RECOMMENDED if you make ALL your configuration changes via menuconfig. It is also
   useful if you get into trouble and want to reset your starting position or change MMU.

(Note that in all cases a BACKUP of your existing .cfg files will be made for reference)

Choose upgrade mode (1-2)?

1. Merge/Refresh (Option 1 — Default upgrade path)
   Merge/Refresh keeps the values in your existing Happy Hare .cfg files. Before menuconfig opens, it lists the values from your .cfg files that menuconfig can show and, if there are any, asks once whether to import them, so menuconfig shows what you are actually running. Only the settings you change in menuconfig during that run are applied to your .cfg files; every other option keeps its value, and new options required by the current Happy Hare release are added. The exceptions are macro gcode: bodies, a few structural options menuconfig always sets, and options the templates no longer contain; see the comparison.

2. Replace (Option 2 — Recommended)
   This is the recommended mode when all configuration changes are managed through menuconfig.
   The Replace mode OVERWRITES any local changes you have made directly to your Happy Hare .cfg files, resetting and regenerating a new configuration based solely on the selections made in menuconfig.
   
   

Both modes end with a summary of changes to your .cfg files, listing each value changed as old -> new. See Choosing an upgrade mode for a detailed comparison, the import prompt, and what can be imported.

Renaming, removing or reordering installed units requires Replace (option 2). Appending a unit also works in Merge/Refresh. See Multiple MMU Units for the editor controls, migration of saved state, and checks after changing the unit list.

Recovering Configuration from a Backup¶

Every normal install preserves the existing mmu configuration directory as a timestamped backup alongside it. If a configuration change goes wrong, run the installer with --prev (or its short form, -p) to choose which saved state to restore:

./install.sh -i --prev

Available MMU configuration backups:
  1) mmu (current config)
  2) mmu.old-20260831-115007 (2026-08-31 11:50:07)
  3) mmu.old-20260830-174053 (2026-08-30 17:40:53)

Choose backup to restore from (1-3)?

The current mmu directory is listed first when it contains a saved .mmu_config; timestamped backups then appear from newest to oldest. Choose a number to restore that directory and continue through the normal installation. If you select a timestamped backup, the installer first preserves your current mmu directory as another timestamped backup, then restores the selected directory and recovers its .mmu_config files into the Happy Hare checkout. This means the configuration you are replacing remains available if you need to return to it.

Use -i with --prev when you want to review or adjust the recovered settings in menuconfig, as shown above. Without -i, the installer applies the recovered settings directly through its normal safe re-install/upgrade path.

For unattended recovery, --last (or -l) recovers the saved .mmu_config without showing the selection menu. It uses the current installed configuration when available, otherwise the newest timestamped backup. --last and --prev cannot be used together, and neither recovery option can be combined with uninstall mode.