Research

I was researching that for a bit until i found some hints that this is possible. It all started with the finding of the original firmware  and a hint how to upload it . But then i found an Issue where the discussion went into the right direction: Obtaining the sourcecode  and an instruction how to update this . And finally also a hint how to extend the timeout .

Fortunately, the user sobieh had changed the firmware in his repository  so that the relay doesn’t need a reset but - and that made it unusable for me - he also changed a couple timeouts and the behaviour of the relay was modified so that it is enabled when the pin is pulled low. For regular cases (where the pc managing the printer is running 24/7) this makes sense but for mine (BTT E3EZ Board with a CB1 onboard) it doesn’t.

So i needed to get into assembly which - thanks to ChatGPT was less complicated than i thought.

Custom Firmware Description

So there it is - the firmware for the BIGTREETECH Relay 1.2 with the following features:

• Shutdown Delay of 30 seconds (allows to shutdown a CB1 or CM4 embedded on your mainboard)
• Startup delay of 30 seconds (allows to start towards klipper without triggering a shutdown)
• Checks every 3 seconds for a changed pin (meaning that it can take up to 33 seconds to shutdown your relay)

Custom Firmware implementation

Prerequisites - Hardware

To implement the modified firmware you will need a serial adapter, e.g. a CH340 ( Aliexpress* or Amazon* ) and a Windows Host.

Prerequisites - Software

• Clone the repository from here .
• Obtain & Install Keil C51 Development Tools 
• Add the path to your C51.exe to the Windows PATH variables
• Obtain and Install Python 3 
• Run:

  1	pip install stcgal

Build Firmware

• Change to the cloned git repository
• Run build.bat

Upload Firmware

This instruction is to be used at your own risk. We are not liable for any damage.

• Disconnect any mains voltage
• Connect the relay board to any USB to Serial adapter
• Run upload.bat COM# where # is your COM port number. To find the number, check the Windows Device Manager
• Reset the board with reset button

For the inner PCB and other accessories, i went on aliexpress and found the components immediately for sale* - just make sure to choose the version for the 1.5 orbiter.

One of the changes to the original design that i found very useful was the model  to replace the lightguide by one with an M6 adapter to directly connect the PTFE tubes.

For the klipper configuration of the sensor it is best to look at the page of the author  - he has described everything over there.

GPIO stands for General-Purpose Input/Output. It refers to the pins on a microcontroller or single-board computer, like the Raspberry Pi, that can be programmed to serve as either inputs or outputs. These pins enable the device to interact with the external world by receiving or transmitting digital signals. Through software programming, developers can configure GPIO pins to read data from sensors (inputs) or send signals to actuators (outputs), facilitating versatile applications like the control of fans, lights or other 3D printing accessories.

Thankfully the pinout is the same on the Manta M4P which is why i was able to extract the data from there  (page 9):

BIGTREETECH describes the pinout of the CM4 the same as the one of the Raspberry pi. However when being used with the CB1, the Pinout Changes. I extracted that information and then used various sources of research to find the corresponding GPIO port: This is the final result:

Update: Now i finally found a mapping in the CB1 repo - check there  if you want to see the mapping for the BTT PI or CB1 MMC version.

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[force_move]
enable_force_move: True

but that didn’t help until I manually set a kinematic position through the console:

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SET_KINEMATIC_POSITION X=10 Y=10 Z=10

Which is as per documentation  perfectly correct. Nevertheless I wanted to move without any previous checks or settings. For this I then worked through the documentation  where it actually is described correctly:

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FORCE_MOVE STEPPER=<config_name> DISTANCE=<value> VELOCITY=<value> [ACCEL=<value>]

This command will forcibly move the given stepper the given distance (in mm) at the given constant velocity (in mm/s). If ACCEL is specified and is greater than zero, then the given acceleration (in mm/s^2) will be used; otherwise no acceleration is performed. No boundary checks are performed; no kinematic updates are made; other parallel steppers on an axis will not be moved. Use caution as an incorrect command could cause damage!

Just to reiterate: Use with Caution, it will move without any boundaries etc.

• EBB36/42 v1.0 uses STM32F072C8T6
  • All Pins but PA0-7, PB0-1, PC0-5, PC13-15 are 5V tolerant
• EBB36/42 v1.1 and v1.2 use STM32G0B1CBT6
  • All Pins but PA4 and PA5 are 5V tolerant

As usual, crosscheck these values, I’m not responsible for any damage resulting out of this article.

References

• https://www.st.com/en/microcontrollers-microprocessors/stm32f072c8.html 
• https://www.st.com/resource/en/datasheet/stm32g0b1cc.pdf 
• https://github.com/bigtreetech/EBB 

References

• Board schematics of the Manta E3EZ 

Gridfinity

You don’t know what Gridfinity is? Check this out:

Fusion 360

Fusion 360 is a cloud-based 3D computer-aided design (CAD), computer-aided engineering (CAE), and computer-aided manufacturing (CAM) software developed by Autodesk. It is a comprehensive design and manufacturing platform that combines various tools and features into a single software package.

Fusion 360 offers a wide range of capabilities and is commonly used in industries such as product design, engineering, architecture, and manufacturing. It allows users to create 3D models, perform simulations and analyses, generate toolpaths for manufacturing, and collaborate with team members in real-time.

Among many other capabilities, Fusion 360 employs a parametric modeling approach, where the relationships between different design elements are defined. This allows for easy modification and editing of designs e.g. like this one.

FusionGridfinityGenerator

A solution to the challenge described at the beginning of this article can be found in a repository of “Le0Michine” on Github: FusionGridfinityGenerator .

The addon provides all kinds of possibilities to generate gridfinity bins and baseplates in Fusion 360. Simply follow the instructions  on Github to get it installed in Fusion 360.

As per the instructions of the installation of Klipper you will have to flash the microcontroller as follows:

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cd ~/klipper/
make menuconfig

During “make menuconfig” select the following settings:

• Enable extra low-level configuration options
• Micro-controller Architecture (STMicroelectronics STM32)
• Processor model (STM32F103)
• Bootloader offset: (28KiB bootloader)
• Communication Interface: (Serial (on USART1 PA10/PA9))

Once you have compiled the firmware using make you can flash it by copying the file out/klipper.bin to a SD card and turning on the printer with the card inserted. The firmware filename must end in “.bin” and must not match the last filename that was flashed.

Resources

• Ender 3 v2 Config from Klipper 
• Klipper Documentation - Installation on the Microcontroller 

On different sites i then found the type of connector (Molex Microfit 3.0 2x2 connector) which is supposed to be connected as follows:

I finally found it here  on github:

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_____________________
| B2 | B1 | A1 | A2 |
|_   ___________   _|

Or more visually (please crosscheck the colors with your extruder of choice!)

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23:29:04 : Erasing memory corresponding to segment 0:
23:29:04 : Not flash Memory : No erase done
23:29:04 : File segment @0x08000000 is not 255-bytes aligned. It will be aligned to @0x07FFFFF8
23:29:04 : Download in Progress:
23:29:05 : Error: failed to download Segment[0]
23:29:05 : Error: failed to download the File

After fiddeling around a bit i finally stumbled across two solutions.

Use Canboot to flash an intermediate firmware

This  failed for me but might a possible path to fix it

Use an older version of the STM32CubeProgrammer

I used version 2.10 of the STM32CubeProgrammer  which solved the case for me at least.

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bed_mesh: min/max points too close together

The reason is relatively simple - it is a bug  in my currently used slicer, OrcaSlicer . It appears to be related to having multiple build plates visible in the slicer - hence it might not happen to you immediately as long as you do not use that feature.

The solution is to either slice only single plates, to switch of “Exclude Objects” or to simply update OrcaSlicer to a version higher or equal to 1.6.2 and you should be able to get rid of this issue.

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Unknown Command "M486"

To me that happened when i switched to Superslicer .

Thankfully it is easy to solve:

• Open Superslicer
• Open your Print Settings
• Search for “Label Objects” (should be in “Output Options”)
• Uncheck the tickbox

That solves it ;)