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Software and Configuration

Troubleshooting firmware issues in Klipper is different from traditional printers. Most problems are not caused by "bad firmware" but by simple errors in the printer.cfg text file.

Understanding the Klipper System

Klipper has two parts:

  1. The Host Software: Runs on a computer like a Raspberry Pi. It reads your G-code and does all the complex calculations.
  2. The MCU Firmware: A simple piece of software on the printer's mainboard that just receives and executes commands from the host.

Section 1: Common Configuration Issues (printer.cfg)

Symptom: The printer was working, but after editing the printer.cfg file, it won't start and the web interface shows an error in a popup or in the console.

Klipper tells you what's wrong!

Unlike other firmwares, Klipper is excellent at diagnosing itself. Always read the error message in the console. It will usually tell you exactly which line in printer.cfg has a problem.

Common printer.cfg Errors:

  1. Syntax Errors:

    • Problem: Simple typos, incorrect indentation, or using a colon (:) where an equals sign (=) is needed.
    • Solution: Carefully review the line mentioned in the error message. Indentation is critical – do not use tabs, only spaces.

  2. Incorrect Pin Names:

    • Problem: You've assigned a pin to a function (e.g., step_pin: P1.24), but the pin name is wrong for your mainboard, or it's already in use.
    • Solution: Double-check your mainboard's documentation or the example configuration file for the correct pin names. Pin names are often prefixed with ! or ^ to invert them, so ensure those are correct too.

  3. Invalid Section or Option:

    • Problem: You have a typo in a section header (e.g., [stepper_z] instead of [stepper_z]) or an option name.
    • Solution: Refer to the official Klipper Documentation to verify the correct names for all sections and parameters.

Always Backup Your printer.cfg

Before making significant changes, always download a backup of your working printer.cfg file.

Section 2: The Klipper Update and Restart Process

  • "Firmware Restart" vs. Full Restart

    • After editing and saving printer.cfg, you don't need to reboot the whole system. Just click the FIRMWARE_RESTART button in your web interface. This quickly reloads the configuration.
    • If you update Klipper itself via the update manager in Mainsail/Fluidd, you may need a full Reboot of the host system.

  • Re-flashing the MCU

    • When is it necessary? You almost never need to re-flash the firmware on the printer's mainboard (MCU). You only need to do this if:
      1. A major Klipper update specifically states that the MCU firmware must be rebuilt and flashed.
      2. You are replacing the printer's mainboard with a different model.
    • Process: The process involves connecting to the host via SSH, running make menuconfig to select your board, make to build the firmware, and then following a specific procedure to flash the resulting klipper.bin file to your board. This is an advanced procedure; follow a detailed guide for your specific mainboard.