Building a DIY public domain low cost stepper motor analyzer

A Former User

Thats awesome, its on my list to try and build one! Thanks for putting this out there man!

zapta

The new PCBs arrive and I like how small and simple they are:

I also added a retraction analysis screen. It is cumulative such that retract 10 steps extruder 3 steps, retract 5 steps will show retraction of 12 steps.

The graph moves in real time so the camera didn't capture it well. The little noise at the bottom of the graph are tiny retractions due to pressure advance (0.08).

I plan to commit the changes to github later today.

fcwilt

Hi,

Have you considered building a small batch of complete units and selling them to us poor souls who would love to get our hands on one?

Frederick

A Former User

I'd could be down for crowd sourcing myself one if such a thing were to be a thing.

zapta

@fcwilt, I would love to do that because I think the makers' 3D printer market needs a tool like this but I can't do it myself. My hope is that someone can pick it up and provide to the community, this exact design or a lower cost version of it (with a stand alone MCU and a dumb LCD). The license is very liberal, non need to attribute, no need to share code changes, commercial OK, etc.

I just created a documentation page in github. It explains the various functions, how to flash the firmware and a BOM.

https://github.com/zapta/stepper_analyzer

A Former User

I'd be happy to build and test (some) additional boards when I make mine, but despite the BOM being about $50-60 (10 seconds guesstimate) statistically it'd be close to double that after shipping, taxes and fees + another $7 to ship it out again. There is no real need for me to source the teensy and screen which brings the rest down to $10-20 (before shipping, taxes and fees). So my location is probably a bit cost prohibitive even when not making a profit.

@zapta is the SD card required for the nextion to run, or just the programming? I'm still waiting for that aliexpress order ... 176 days is the 2020 shipping highscore:/

fcwilt

@bearer

If you've got a PayPal account I'd buy a unit from you.

Frederick

A Former User

@fcwilt i do. i've posted an informal doodle https://doodle.com/poll/hhw2iyirf8fctmn4 where interest could be gauged, but admittedly very skeptical as global shipping is very unreliable these days.

arhi

@zapta wanna pick your brain a bit .. why did you go with analog output current sensing and not with one with integrated ADC with spi output? Something like LMP92064 for e.g. comes to mind?

I am now deciding between LMP92064 and ACS70331 + AD7705 and it looks like ACS70331 + AD7705 will go in final product 'cause I need the resolution but since you are using the ADC on the teensy I guess LMP92064 would be easier solution ?! Or you went by the price (LMP92064 is ~3x more expensive locally, I guess it's same everywhere)

zapta

@bearer said in Building a DIY public domain low cost stepper motor analyzer:

@zapta is the SD card required for the nextion to run, or just the programming

Just for programming and should be removed for the Nextion to function. I just updated the documentation to clarify it.

zapta

@fcwilt said in Building a DIY public domain low cost stepper motor analyzer:

If you've got a PayPal account I'd buy a unit from you.

Just a suggestion. One payment method that worked for me in the past is amazon gift cards. Buying often on amazon, credit is almost like cash, and cards can purchased online at any amount and the gift card number can be sent by email.

zapta

@bearer said in Building a DIY public domain low cost stepper motor analyzer:

@fcwilt i do. i've posted an informal doodle https://doodle.com/poll/hhw2iyirf8fctmn4 where interest could be gauged, but admittedly very skeptical as global shipping is very unreliable these days.

I believe that BOM could be reduced well below $20 with a dumb LCD (example below) and a stand alone MCU (vs the Teensy 4.0). All is required is somebody that is proficient with writing firmware and can re implement the UI for the dumb LCD.

https://www.buydisplay.com/serial-spi-3-5-inch-tft-lcd-module-in-320x480-optl-touchscreen-ili9488

https://www.buydisplay.com/lcd-3-5-inch-320x480-tft-display-module-optl-touch-screen-w-breakout-board

Edit: another option is to drop the display and use a USB or Bluetooth attached computer or phone/table for the UI. The voltaic isolation of the current sensors will make it safe for the USB connection. This opens new possibilities such as recording, correlating signals from multiple steppers (e.g. X/Y in core XY), and so on. With a stand alone, non Teensy standalone MCU, this will be a tiny and inexpensive device that can be plugged anywhere. BTW, the Teensy and Nextion consume ~250ma so a battery operation is also feasible. Many great possibilities that wait for the right entrepreneur.

zapta

@arhi said in Building a DIY public domain low cost stepper motor analyzer:

I am now deciding between LMP92064 and ACS70331 + AD7705

The main advantage of the ACS70331 for this application is the voltaic isolation.

The LMP92064 would kind of work for a single stepper coil if it's ok to have the circuit floating with the stepper signal but wouldn't work for two coils since they don't have a common ground.

BTW, you can find it in different current ranges and polarity (directional vs bidirectional) https://www.digikey.com/products/en?FV=-5|62165

fcwilt

@zapta said in Building a DIY public domain low cost stepper motor analyzer:

Just a suggestion. One payment method that worked for me in the past is amazon gift cards. Buying often on amazon, credit is almost like cash, and cards can purchased online at any amount and the gift card number can be sent by email.

I never thought about that approach. I will remember it.

Thanks.

Frederick

arhi

@zapta said in Building a DIY public domain low cost stepper motor analyzer:

@arhi said in Building a DIY public domain low cost stepper motor analyzer:

I am now deciding between LMP92064 and ACS70331 + AD7705

The main advantage of the ACS70331 for this application is the voltaic isolation.

Yes, LMP is not isolated .. I believe there are some isolated ones but ACS70331 + AD7705 is probbly better option anyhow

A Former User

@zapta said in Building a DIY public domain low cost stepper motor analyzer:

I believe that BOM could be reduced well below $20 with a dumb LCD (example below) and a stand alone MCU

Between just wanting the one and being the kind of guy that thinks a .csv file is a perfectly acceptable user interface buying the fancy screen makes the most sense to me. For the Teensy I'm thinking put headers on it so less hand assembly and it can be repurposed if needbe.

Its also easier to offer to hand assemble 10 or simple parts than a MCU with supporting parts

I'll help the community as best I can, but I don't I have the ambition or capability to be very entrepreneurial. Still, my hat off to you for your work on this!

edit: Total Nextion noob wasn't sure which display to use but seems the Basic NX4832T035 that i accidentally had on order will do the trick (the Enhanced NX4832K035 will readily compile but the others will either crop or not scale well to/from 480x320)

A Former User

@fcwilt I just placed another order for the bare pcb's as the first never arrived. Fingers crossed PCBway will deliver:)

fcwilt

@bearer said in Building a DIY public domain low cost stepper motor analyzer:

@fcwilt I just placed another order for the bare pcb's as the first never arrived. Fingers crossed PCBway will deliver:)

Were you able to determine what happened to the original order?

Frederick

A Former User

@fcwilt nope; tracking said package left china but never arrived at customs - has been a slight increase in that this year and due to delays extra waiting before re-ordering. Ignoring wasted time its not a big deal, the bare boards are cheap 10 for $13 shipped iirc.

zapta

@bearer, FYI, a good resource for PCBs is https://pcbshopper.com.

I am ordering from jlcpcb. for $20, 5PCBs arrive in 6-7 days from order time. For ~9$, within a few weeks.

BTW, I am working toward a lower cost one, for curiosity, with a standard 'dumb' TFT using lvgl library which was recommended here and a low cost MCU. Had some progress but it's going slowly, mostly because the MCUs I used had insufficient memory (STM32F103, first with 64K rom and later 128K), got now a STM32F401CCU6 board (they are still cheap) and will give it a try.

The existing design with Nextion is still the way to go if you want something working, and it's very easy to add new functionality.