Configuration

Configuration

Runtime configuration: guppyconfig.json

Runtime configuration lives in guppyconfig.json. The shipped template is debian/guppyconfig.json; on the printer it is installed to /usr/data/guppyscreen/guppyconfig.json with the <GUPPY_DIR> and <PRINTER_DATA_DIR> placeholders substituted by the installer.

Top-level fields

Field	Meaning
default_printer	Key of the active entry in printers
display_rotate	Framebuffer rotation. 2 (180°) is the KE default — the screen is mounted upside-down (see below)
log_path	Log file path (resolves to /usr/data/printer_data/logs/guppyscreen.log on device)
thumbnail_path	Directory for cached gcode thumbnails
wpa_supplicant	Path to the wpa_supplicant control socket (used for WiFi management)
guppy_init_script	Command used to (re)start the service, e.g. service guppyscreen
printers	Map of named printer configurations (see below)

Per-printer fields

Field	Meaning
moonraker_host / moonraker_port	Moonraker address (default 127.0.0.1:7125)
moonraker_api_key	API key string, or false if not required
display_sleep_sec	Screen blank timeout in seconds
monitored_sensors	Sensors shown on the dashboard. Each has id, display_name, controllable, color
default_macros	Macro name → gcode mappings (e.g. cooldown, load_filament, unload_filament)
fans	Fans to surface in the fan panel
log_level	spdlog level (e.g. debug, info)

Default monitored sensors

The shipped template monitors Extruder, Bed, and MCU Temp (temperature_sensor mcu_temp). This default applies to fresh installs only — an existing on-device guppyconfig.json must be edited by hand to change which sensors are shown.

Display rotation (KE-specific)

The KE screen is physically mounted upside-down. The kernel display driver rotates the framebuffer 180° to compensate, so GuppyScreen must pre-rotate 180° for the two rotations to cancel out:

• display_rotate: 0 → screen appears upside-down
• display_rotate: 1 → 90° off (wrong axis)
• display_rotate: 2 → correct (KE default)

Build-time options (environment variables)

These are read by the Makefile at build time, not at runtime:

Variable	Effect
CROSS_COMPILE	Toolchain prefix (e.g. mipsel-linux-). Unset = simulator/x86 build
GUPPY_SMALL_SCREEN	Enables the 480×272 layout and reduces the default font to montserrat_10
GUPPY_ROTATE	Compiles in rotation support
GUPPY_THEME	material (default), zbolt, or a colour theme name (e.g. blue)
GUPPYSCREEN_VERSION	Version string shown in the System panel
EVDEV_CALIBRATE	Enables touch calibration
SIMULATION / (no CROSS_COMPILE)	Builds the SDL simulator with the SIMULATOR define and links -lSDL2

Font note: With GUPPY_SMALL_SCREEN, LV_FONT_DEFAULT is montserrat_10 (set in lv_conf.h). Most widgets inherit this; a few panels set explicit fonts. This is the value in the current source — some older notes still reference montserrat_12.

Themes

Colour themes are JSON files in themes/ (blue, green, pink, purple, red, yellow). Icon sets are compiled in via GUPPY_THEME (material is the default; zbolt selects the Z-Bolt icons).