Mellow FLY SHT36 Pin configuration errors

General Discussion
1

Basic Information:

Printer Model: Voron Trident
MCU / Printerboard: Fysetc Spider v2.2
Host / SBC: Raspberry pi 5 (Bookworm)
klippy.log
klippy (8).log (1.0 MB)

Fill out above information and in all cases attach your klippy.log file (use zip to compress it, if too big). Pasting your printer.cfg is not needed
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Describe your issue:

Hello, I have an issue where I can’t get past the error message Pin 'PB5' is not a valid pin name on mcu 'sht'.

The host is a RPi 5, it is conected to a protoboard with RPi pico (RP2040) and a CAN transceiver (MCP2551) as a USB to CAN bridge which in turn is conected to the FLY SHT36 Toolhead board. During these trial runs the mainboard and the toolhead board were powered up at 24V.

I have checked that I compiled klipper for the right MCU on the FLY SHT36 (STM32F072) and flashed it via USB using dfu-util, and yes, the BOOT0 jumper was removed afterwards and it was showing up in the CAN0 scan.

I have tried changing the sht:PB5 pin to a board pin and that error was cleared but then one of sht fan pins threw the same error.
Here is the link to Mellows “Wiki” for the pin map of the board: Fly SHT-36 Pin Definitions | Mellow Products Documentation

Other things I have tried is increasing the buffer length on the bus and reflashing the firmware but without success…
Also the printer.cfg file is not finished so there might be some weird things in there but nothing that could cause this issue.

I really appreciate all the help that I can get since this is not the first time I have been driven mad by the CAN protocol… Thanks.

2

MOSTLY SOLVED

If someone finds this in the future: follow esoterical can bus tutorial word by word and distrust any hardware that its not in a sealed bag.
The most important things to check:

  • Do you have the same bitrate in your networkd file as in your USB to CAN bus bridge? You might have been switching between bitrates and forgot to change the parameter in networkd
  • OK, there is a device detected when i run the script to list devices on the CAN bus but it never goes into Katapult, what is happening? If you are using a RP2040 based USB to CAN bus bridge that is running klipper im sorry to tell you that is your USB to CAN bus bridge… That was the pitfall above, if you tell klipper that the UUID of your bridge is the toolhead board klipper is going to be as confused as you are. If you are not using a RP2040 based bridge and nothing shows up you are in the same scenario.

To add to the last scenario, if your toolhead board happens to be a RP2040 based one too, it will all go fine until you try to start some kind of comm with another chip (e.g. tell the extruder to extrude) you will be met with a comms error as you are sending that message to the bridge.

If you are sure that your USB to CAN bridge is functional, your toolhead board is flashed with the correct Katapult config and the bitrate on all devices match and the device still does not show up when performing a CAN bus scan, cut your loses and go buy a new board, the transceiver on the toolhead board or the bridge is most likely absolutetly cooked. The time you are going to spend troubleshooting the hardware is more valuable than a 15€ board…

Hope this helps someone.