LV8727 stepper configuration information

@Brandon_Satterfield sent me the following stepper drivers for my OX build:

The silkscreen on the back is mostly in chinese without translation, and also doesn’t make sense; for example, it says that 128 microsteps per step and 20 microsteps per step are configured the same way.

It looks like the information on aliexpress makes more sense:

The rest of the information might be useful too:

Seems there was some pictures floating about of the internals of all in one control box, I’d follow those settings. Seems it was 1/16 micro step, although you could use a crazy high micro step (128) as your on 2.8A steppers with 4A drivers (intentional). I’ll look about.

Note that the two control connections are different. One is EN CLK DIR GND and the other is EN DIR CLK GND — it’s not a silkscreen error, I confirmed with multimeter.

I’m hoping that 3.3V is enough so that I can drive it from an ESP32 without a level shifter in the way. :slight_smile:

Thumbs up brother, absolutely correct!

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Are you suggesting that I should turn the driver current all the way up to 4A with 1/16 microstepping?

I started with as close as I could eyeball to 2.8A and 1/2 microstepping to see what it would be like, and… it doesn’t sound very good. 1/16 microstepping sounds a lot better. I haven’t turned the current up. It runs, but I haven’t put bit to wood yet.

Air-cutting imaginary OX plates from .gcode file from @Brandon_Satterfield now. And from another discussion…

I know that sometimes when people use steppers in a heated enclosure for 3D printing ABS and similar plastics, they damage the steppers. But I’m familiar with how how the 1A or so steppers on my printers get.

I’m running MT-2303HS280AW for all four steppers. Temperature ratings:

| Ambient Temperature | -20°C~+50°C |
| Temperature Rise | 80°C Max.(2 phase on) |

That seems to say they are rated to 130⁰C which seems hotter than I want to experiment with. So far, the X and Y steppers are just under 100⁰F and Z, which I set a little higher on current (not measured, of course :roll_eyes:) is 120⁰F, so probably there’s some headroom here at 1/16 microstepping. So @Brandon_Satterfield, did you run these 2.8A steppers at 4A with 1/16 microstepping?

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No, I kept them at the stock amperage but always had motors fully locked.

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I did first cuts in styrofoam in order to take things one step at a time, and I appear to be skipping steps. My X and Y steppers are running near ambient temperature. This makes me think that I really need to actually measure the current and not go by the graphic in the documentation, which I kind of expected anyway.

(Wow I was glad I used a dust boot and vacuum while cutting styrofoam!)

Edit: I finally realized that I have $1=250 instead of $1=255 and not sure how that happened. Need to change that and try again.

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Even with $1=255 set, axes are doing uncommanded moves. I got a hole from drilling (only Z movement, X and Y stayed at 0) that looks like this:

That’s not a round hole. And I felt the Y steppers actually stepping while it was drilling, with this gcode:

G0 Z9.906
G0 X0.000 Y0.000
G1 Z-6.350 F8.47
G0 Z9.906

Makes me wonder whether 3.3V signal is near a threshold for those stepper drivers and electrical noise is making them sense steps that aren’t there. I also got a phantom Y pin pressed notice once (the gantry was nowhere near the Y limit, and there was nothing anywhere near the switch to engage it).

Here’s my second (and, overlapping at the bottom, part of the my first) attempt to do a practice cut in styrofoam:

Those circles that aren’t quite coaxial are intended to be a 1 1/8" wide circular groove.

Should I be using a level shifter to clock the steppers?

It worked better with $1=10 than with $1=3; the hole I drilled looked like a hole instead of a backward L. But the Y axis was still hunting slightly during drilling, the circles were still offset, and there was still some step-over on the outside contour cut.

I also disconnected the limit switches entirely to make sure that I wasn’t experiencing electrical noise on the stepper lines.