# Klipper loses connection to MCU after firmware restart

**URL:** <https://klipper.discourse.group/t/klipper-loses-connection-to-mcu-after-firmware-restart/11443>\
**Category:** General Discussion\
**Created:** [November 7, 2023, 10:18pm UTC](https://klipper.discourse.group/t/klipper-loses-connection-to-mcu-after-firmware-restart/11443 "2023-11-07T22:18:02Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![TheSchiffbauer](https://avatars.discourse-cdn.com/v4/letter/t/ea666f/32.png) [@TheSchiffbauer](https://klipper.discourse.group/u/TheSchiffbauer)\
**Post date:** [November 7, 2023, 10:18pm UTC](https://klipper.discourse.group/t/klipper-loses-connection-to-mcu-after-firmware-restart/11443/1 "2023-11-07T22:18:02Z")

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### Basic Information:

Printer Model: Creality CR 10 V3  
 MCU / Printerboard: ATMEGA 2560  
 [klippy (2).log](https://klipper.discourse.group/uploads/short-url/pr4ytfVfJsKqNnV3xkObcUxrfVF.log) (122.3 KB)

Hello,

I installed MainSailOS a few times now and I’m getting always the same result:  
The MCU is always loosing connection after a firmware restart.

In the next step I did all the steps, that are recommended under: How To Troubleshoot?.

I removed the application Modemmanager before I flashed the motherboard from my Printer.

Then I reduced the Baudrate to 115200 and set the communication interface to UART0 and flashed the mainboard again.

And the MCU is still loosing the connection to the rapberry. Afterwards I made sure, that the serial Port is correct.

If I start my Printer first and afterwards the raspberry the connection is stable and does not crash while i’m printing.

I even set the max. current from my USB-Connection to 0V (I read, that this could be the Problem).

But I’m still getting the output from the command dmesg like it is shown in the How-To-Troubleshoot directions as the negativ example.

Unfortunately I’m relativly new in the Klipper scene and I dont now how to solve my problems.

I hope one of you guys can help me with my problems.

Thank you in advance.

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\
**Post date:** [January 6, 2024, 10:18pm UTC](https://klipper.discourse.group/t/klipper-loses-connection-to-mcu-after-firmware-restart/11443/2 "2024-01-06T22:18:25Z")

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