This config extensively use [board_pins] sections to simplify the hardware configuration. In Klipper, once a [board_pins] is defined, then the pin aliases can be used in all the hardware sections to make them more readable. If you want to get more info about it, have a look here in the official Klipper documentation).
In the design process of this generic config, some rules and naming convention were defined and used in every preconfigured board_pins files for all the most used MCUs of the market. Then these aliases where used everywhere in this config.
NOTA :
[board_pins]sections can not contain pin modifiers like!,^and~. Moreover, when multiple MCUs are configured at the same time, all the aliases used in the hardware sections have to be prefixed with the MCU name. This is a current limitation of Klipper that is limiting the "genericity" of this config: so please be sure to check all the harware section and pin definitions in all the file that you want to include in your config.
All the predefined board_pins files can be found in config/mcus. You can always adjust them to your needs.
[XYZ1-3E]_STEP: drivers step pins[XYZ1-3E]_DIR: drivers dir pins[XYZ1-3E]_ENABLE: drivers enable pins[XYZ1-3E]_TMCUART: drivers UART pins
[XYZ]_STOP: classic axis endstops pinsPROBE_INPUT: probe pin
E_HEATER: hotend heater cartridgeBED_HEATER: bed heating pad (or bed SSR)
E_TEMPERATURE: hotend temperature sensorBED_TEMPERATURE: bed temperature sensorCHAMBER_TEMPERATURE: chamber temperature sensorELECTRICAL_CABINET_TEMPERATURE: electrical cabinet temperature sensor (not really used in the config, but if present, this sensor is added to the Mainsail / Fluidd web interface as an additional info)
E_FAN: hotend fan. This fan should stay at 100% whenever the hotend is hot, so a PWM capable pin is not mandatoryPART_FAN: part fan used during the print. This pin should be a PWM capable pin to allow power modulationFILTER_FAN: pin for the recirculating filter (such as a Nevermore filter). This pin should be a PWM capable pin to allow power modulationCONTROLLER_FAN: pin the fans that add airflow on your MCUs
LIGHT_OUTPUT: simple chamber lights (such as 24v leds or 24v fcob light bars)LIGHT_NEOPIXEL: neopixel chamber lightsSTATUS_NEOPIXEL: toolhead Neopixel lights (such as the one used on the Voron StealthBurner toolhead)
RUNOUT_SENSOR: filament motion sensor pinSERVO_PIN: servo pin for a mechanical and movable probe dock (such as the ones that are commonly found on the Voron V0 mods)
For more information on the boards and pinouts, please see directly the manufacturers website or github: