Mcu: Serial connection closed / Timeout on connect / Wait for identify_response

mcu: Serial connection closed / Timeout on connect / Wait for identify_response


The printer-board / MCU did not respond to the connection attempt of the Klipper Host until finally the serial connection timed out and was closed. Often, these 3 errors will go hand in hand in the klippy.log


  • Hardware issues between the board and the SBC, e.g. USB port, USB cable etc
  • Wrong parameters during make menuconfig when building the firmware for the board
  • Firmware not correctly flashed to the board
  • Dead board

Potential solutions

  • Follow the dmesg procedure to check if and how the board registers in the operating system
  • Following symptoms in the dmesg output point to either a not correctly flashed board or some hardware issues
    • It registers, but quickly gets disconnected again
    • It registers, but around this process are some USB related errors in the dmesg log
    • The dmesg output shows simply nothing, when the board is freshly connected
  • Check and verify the parameters used during make menuconfig
  • Repeat the flashing process and pay special attention to the instructions given on top of the example config files
  • Use different SD cards (preferably below 8 GB) for the flashing process
  • Make sure the board has proper contact to the SBC. Use a high quality USB cable
  • Check with ls /dev/serial/by-id/* for the presence of the board and compare the output to the settings [mcu] block
  • Read Issues flashing the printer board for more detailed information