# Unable to Connect MCU

**URL:** <https://klipper.discourse.group/t/unable-to-connect-mcu/12000>\
**Category:** General Discussion\
**Created:** [December 1, 2023, 7:17pm UTC](https://klipper.discourse.group/t/unable-to-connect-mcu/12000 "2023-12-01T19:17:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ThunderClap](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThunderClap](https://klipper.discourse.group/u/ThunderClap)\
**Post date:** [December 1, 2023, 7:17pm UTC](https://klipper.discourse.group/t/unable-to-connect-mcu/12000/1 "2023-12-01T19:17:55Z")

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### Basic Information:

Printer Model: Ender 5 Plus  
 MCU / Printerboard: BTT Skr Mini E3 v3.0  
 BTT PAD 7  
 ‘sudo dmesg’  
[sudodmesgbtt.txt](https://klipper.discourse.group/uploads/short-url/ulZI8hqnFlVOsqPFjHXEhg2yoDj.txt) (33.2 KB)  
 ‘klippy’  
[klippy(2).log](https://klipper.discourse.group/uploads/short-url/qpFDxBkRlpptlEWRAhXsWt0Qrw4.log) (464.8 KB)

### Describe your issue:

I’m sorry there was a lot going on in the klippy log. I was chasing down a BTT .cfg error and now I am chasing my tail. Not sure where to begin. Most recent entries into the log I believe are saying there is an MCU connection issue. I have done the `ls /dev/serial/by-id/ ` and have gotten a reply with “usb-STMicroelectronics\_MARLIN\_STM32G0B1RE\_CDC\_in\_FS\_Mode\_205132455942-if00”. This is what I entered into the printer.cfg under [mcu] with serial: prefacing it. No clue whats going on now.

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<div class="post-metadata">

**Author:** ![ThunderClap](https://avatars.discourse-cdn.com/v4/letter/t/91b2a8/32.png) [@ThunderClap](https://klipper.discourse.group/u/ThunderClap)\
**Post date:** [December 1, 2023, 7:45pm UTC](https://klipper.discourse.group/t/unable-to-connect-mcu/12000/2 "2023-12-01T19:45:09Z")

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SELF RESOLVED. Leaving answer here for others in case they have the same issues. Notice that my previous USB output included MARLIN in the name? I am converting from marlin to klipper, and my SD/TF card was NOT flashing. I switched to my 3rd card and the flash finally took, if all else fails… try a different TF card.

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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 1, 2024, 5:45am UTC](https://klipper.discourse.group/t/unable-to-connect-mcu/12000/3 "2024-01-01T05:45:28Z")

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