Hi everyone,
The stepper motors I’ve bought come with driver PCBs. I’d like to use them instead of using a sangaboard, Is there a suitable STL for a base to allow this? I’ve both Nanos and Unos in my motley collection of microcontrollers.
I’ve nothing against the Sangaboard (though I’ve yet to find a schematic for version 2) but I just want to use what I have without milling a Sangaboard.
Though I must admit the standard driver boards are a pain to use in a permanent installation. That is, one without DuPont cables…
Stay safe,
Steve
There is another thread on here, where someone designed that. I’ll look for it.
Edit:
It was @Orgeman that designed it. A link is in this post.
William,
Thanks! I believe I’ve found a source of motor driver boards with a better shape. They should be here on Sunday. I’m a bit old fashioned as I don’t want a rats nest of DuPont cables which will inevitably fail. I was considering removing the driver chips and the motor connector from the standard boards and putting them on a perf board. The chips are easy because they are socketed but I’ve had no success with desoldering the motor connector without damaging it.
Thanks again, it’s a really interesting project and I’ve already been asked to make one for an MSc Microbiology student.
Regards,
Steve
Nice 
I completely agree on the dupont connector rats nest! It’s worth noting that the motor connectors are also on a standard 2.5mm pitch, so you can use regular male header pins as a readily available alternative. It’s quick and dirty (and non-locking) but Sangaboard v1 did it, and it worked just fine for development purposes. I don’t know if Valerian ever uploaded the v1 PCB design (which was just a Nano, two ULN ICs, and header pins for the motors) but he hand-etched it on a single sided board.
I’ve bodged a solution using a Nano and three controller boards as shown in the picture. This is just for testing. I’ve tried two types of controller board, neither is breadboard friendly as the pins are above the board not below. I don’t really want to design and mill a PCB until I’ve got everything working. I’ve a few ideas for modifications to the illumination stage which I want to add which aren’t on the sangaboard. Also I want to be able to run it from batteries so I need voltage regulation on board and a choice of inputs.
So far it’s been fun. Today’s task is to figure out how to resolve the preprocessor statements in the Arduino code to tell it the appropriate pin settings. But that’s another topic.
Are we able to use a CNC shield board which are possible to controller 3 stepper motors in a small form factor?
Hi @jenovauh all of the CNC boards I’ve seen are built for bipolar motors, usually the much larger NEMA17 type. We’ve stuck with the micro geared steppers that we use because they’re cheap and low-power, because one of the things we care about is being able to run for a long time on batteries (e.g. in a Tanzanian clinic, where power outages are common).
There are two options:
- modify the 28BYJ-48 motors that we use to remove the “common centre tap”. This requires some dissassembly and the removal of a soldered wire. After doing this, you can drive the motors with bipolar drivers. This has some benefits (higher torque, wider selection of drivers) but we have avoided putting it in the main instructions because it’s using the motors off-spec, and it puts a lot of people off building the microscope.
- modify the microscope to use bipolar steppers. This has, I believe, been done by a team in Peru, though I’m not sure if they have shared the design yet - I should check that out! The disadvantage is that the NEMA17 motors (the most common and usually the cheapest, as they’re used in 3D printers and many other devices) are much heavier and much more power-hungry than the micro-geared motors we use at the moment.
In either case, you’d then need to replace the Python module driving our custom motor board with another one that communicates with a standard CNC board. I suspect you could use @B.Diederich’s code for this, I think he has got the server working with a GRBL board, I’m not sure if that uses the same G code as the 3D printer boards or not, but I’m pretty sure you could flash a cheap CNC board with the GRBL firmware - so you might not need to write any custom code.
Hi,
I have explored this option as well and found this:
The main problem I see is while there are drivers that run at 5V, most of-the-shelf CNC or 3D printing board are designed for 12-24V. Some of them do have internal 5V but most won’t be able to sustain a Pi. So your options are an extra PSU/Step-down or a 2 rail PSU and all of them add plenty of cost.
@r.w.bowman The microscope only move around so all g-code compatible boards should work.
Hey! Yeah, we made some experiences with the GRBL protocol. Happy to help out. Indeed the CNC Shields e.g. for Arduino need 12V supply voltage.
Given that you’re driving a coil twice as long if you switch from unipolar to bipolar, and that 12v is not so different from 10v, would it be OK to drive a 5v 28BYJ-48 stepper with the centre tap removed using a 12v board? Given that most of those boards are constant-current controlled anyway, perhaps it would be OK, provided the current was set low enough not to overheat the motor.
This is a genuine question though, I am not suggesting I know it will work!
I havent fiigure out how to do that, At the moment I am having issue with arduino nano clone which is using CH340 driver.
Some suggestions for getting the Nano to work are in the thread Motor Wiring and Arduino code - Request Help
Hi WilliamW, thanks again and i will try that and see if it helps.
Anyway I tested change the code, just doesnt work for me. Need to figure out how to make CH340 to work with Pi. Should be driver detection issue.
I managed to solved the clone Arduino Nano issue by installing sangaboard firmware in raspberry pi. Is this steps necessary? I did not see this step in all the guides at all. Or maybe I had missed out on that.
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Hi @jenovauh I’m not quite sure what you mean by installing Sangaboard firmware on the Pi: I thought the issue was that you couldn’t see the board in order to upload the firmware to it?
You are right, the CH340 usually is a driver issue. It’s possible that the pi, being a Linux system, has the CH340 drivers pre installed - that is a useful point to note.
