Connection issue between BTT SKR Pico and RPi

General Discussion
1

Hello,

I’m experiencing a connection issue between my BTT SKR Pico (RP2040) and my Raspberry Pi 3B. Despite numerous attempts over several days, I can’t establish a connection. The connection is not detected via USB or UART in normal mode (despite changing the firmware settings accordingly). I suspect the issue might lie in my process of flashing the board(-s) but I am not sure what exactly is wrong.

Hardware & Software Details

  • Board: BTT SKR Pico (RP2040)
  • Firmware: Klipper v0.12.0-396 (installed via KIAUH script/ already included in the raspberry klipper image)
  • PC OS: Raspbian Klipper Image on Raspberry Pi 3B (tested with other PCs as well, all Linux-based, Debian 12 and Ubuntu Server 24.04 LTS)
  • Connections Tested: USB and UART (multiple cables tested for both)
  • klippy.log:
    klippy.log (19.1 KB)

Symptoms

  • Error Messages: No error messages are displayed, but the board is not recognized. The error has been occurring since I reflashed the board because no connection to the board was possible after the last complete system and klipper update.
  • Connection Behavior: Both boards doesn’t show up in “dmesg” at in “normal”-mode.
  • Tests: I’ve tested multiple USB cables and other PCs, all with Linux. The boards worked in DFU/flash mode (both boards), but never in normal mode.

Troubleshooting Steps Taken

  • Firmware Check: Klipper firmware was flashed via the official method (using make menuconfig, make, transferring klipper.uf2 to a pc via scp, setting both jumpers for usb power and boot mode, connecting the board to the pc, transfer the file to the board, disconnecting boot jumper, pressing reset switch and then testing the board back at the klipper host).
  • Other PC or Cable: Tested with other Linux-based PCs and multiple USB-C cables.
  • Logs: dmesg shows no detection of the board in normal mode, only in DFU/flash mode. While testing various older Klipper versions, a connection was briefly established once, but after pressing the reset button, it disappeared again.

“make menuconfig”-settings:

                     Klipper Firmware Configuration

[*] Enable extra low-level configuration options
Micro-controller Architecture (Raspberry Pi RP2040/RP235x) —>
Processor model (rp2040) —>
Bootloader offset (No bootloader) —>
Flash chip (W25Q080 with CLKDIV 2) —>
Communication Interface (USBSERIAL) —>
USB ids —>
() GPIO pins to set at micro-controller startup (NEW)

Expected Behavior
The board should be detected in normal mode via USB and UART and function as expected. It worked fine previously for many months with the same setup. (Pico Board with Raspberry and UART connection)

Additional Info
I suspect the issue might be in my flashing process. I tested with both the current and a brand-new BTT SKR Pico board, to rule out an electrical fault.

I would be very grateful for any suggestions as to what I am doing wrong.

Thanks in advance!

2

See SKR-Pico/Klipper at master · bigtreetech/SKR-Pico · GitHub

As a bare minimum you are missing Basic Configuration - Step 4

3

Thank you for your response! I checked the SKR-Pico/Klipper GitHub as suggested. Unfortunately, when running the command ls /dev/serial/by-id/*, it doesn’t return anything that I can use in the config.

testuser@test:~$ ls /dev/serial/by-id/*
ls: cannot access '/dev/serial/by-id/*': No such file or directory

Additionally, I don’t see any connection to the board in the USB devices listed by lsusb or dmesg. Could you help me understand why this might be happening?

4
  1. I’d recommend compiling the firmware for USB connection, since with UART you won’t have any indication via ls /dev/serial/by-id/* if the flash was successful.
  2. Follow the instructions in the above link.
  3. If you don’t see the respective output in ls /dev/serial/by-id/* or in dmesg, the board is either not correctly flashed or not properly connected (assuming it’s not simply dead).
5

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