Hello Dr. Florian,
I attempted to replicate your Otto liquid handler using the information provided on the Open Liquid Handler website. However, I’m encountering issues with the TMC 2260 board and the SPI port communication. Initially, I tried running it with 5 stepper motors, but it didn’t work. I then attempted to run one Stepper motor with TMC 2260 using the SPI connection, but it still didn’t work. Interestingly, when I tried using the TB6600, it worked fine. Could you please help me troubleshoot this issue?..Can I able to use backbox instead of using all these wires and boards?(give me your suggestion).
Thank you.
Hi Kowthaman 
If you are unable to get the SPI communication working, then I strongly recommend selecting a more straightforward stepper driver, like the TB6600. The TMC drivers really just offer quieter operation, which is not necessary for the performance of OTTO.
I do regret not using a more out-of-the-box platform, such as the Blackbox or a stepper motor shield for the publication. As you pointed out, this would significantly cut down on wiring, but I didn’t like the idea of a commercial product that could become obsolete. Also, to actuator the plunger on the pipettor the control system must be able to interface with a fourth motor (most existing solutions are 3-axis only). The new OpenBuilds Blackbox uses an Esp32 microcontroller and likely can be programmed with the Arduino code available on the OpenLiquidHandler website. You can also use the Y2 motor for the pipettor. You will need to identify, which pins on the ESP32 are controlling the Step/Dir signals on the corresponding stepper drivers. Also, if you plan to use the two lasers for checking the tip straightness and floating head, you will need further modifications.
I see that you have reached out to me multiple times over email, website form, Instagram, and this post all within the span of a day. I want to make sure that you have the correct expectations for this DIY project. I can try my best to answer specific question when you provide context (code, wiring diagrams, pictures, etc.), but it will not be possible for me to produce new content for OTTO, including new code for an alternative motion setup or new mechanical designs.
David
Dr. Florian,
Thank you for your response. I am encountering some errors with the Python code you provided. Could you please share an updated version of the OTTO Python file? It would be very helpful.
Thank you!
I have shared the most up-to-date file. Could you please describe the errors you are having?
Hello Dr. Flo,
I hope you are doing well. I have been diligently working on reconstructing your invention, but despite my persistent efforts, I have faced repeated challenges. Unfortunately, I have fried over 20 stepper drivers, and I am struggling to identify the root cause of the issue.
I have attached some reference images for your review. In the first image, you can see that the chip leg responsible for the VS pin is damaged. The second image shows my complete circuit setup. To mitigate noise, I have added a ferrite bead to the VS line, but the problem persists. Could you please give me some tips to over come the issues like to avoid noise, frying stepper driver and voltage fluctuations
Given that I have been working on this for the past six months without a clear resolution, I would greatly appreciate any guidance or suggestions you may have on how to address this electronic issue. Your advice would be invaluable at this stage.
