Microstepping question - 1/16 or 1/32 or both?

Controllers Smoothie
1

Greetings -

I recently bought a new Smoothie. Used an existing config, but it resulted in motion (Cartesian 'bot) that was exactly half what it should be. It would seem this new board uses 1/32 microstepping, whereas the old used 1/16.

And indeed, the documentation seems split. The stepper motor page (forum[dot]smoothieware[dot]org/stepper-motors) says 1/16, but the Smoothieboard page (smoothieware[dot]org/smoothieboard) says 1/32.

Obviously, I can change the steps_per_mm in the config, but:

  1. I would like to have one config that works across all boards, if possible. Is there a standard? Or a way to set this via the config?

  2. I’m also having trouble getting the 'bot to run at the same feed rates as before, presumably because there is less torque at higher microstepping settings? Tried upping the motor current, but they’re only rated for 2A, and it was already up at 1.6A. Is it safe to turn it up to 3.2A to get the equivalent torque?

Thanks,
-Dave Z.

Imported from wikidot

2

Also, my board — labeled 1.1 in the corner by the QC PASS sticker — has A5984 chips, but the schematic for v1.1 shows A4982s (which don’t even have 1/32 microstepping). What’s going on here?

3

I fixed the wiki page so it shows 1/32 now.

  1. I’m not sure what you mean

  2. You need to set your current exactly at the precise current rating of your stepper motors, higher values will cause lots of trouble. You can’t go higher than 2A, by design.

4

So I just checked, and the old Smoothieboard I was using is version 1.0b. It has Allegro A4982 drivers, which max out at 1/16 microstepping. When I built the config, I used 1/16 microstepping to calculate the alpha_steps_per_mm and so on. Then, I got a new board and the config didn’t work, as the new board has A5984 drivers and uses 1/32 microstepping. That config file is checked in to a github repository (of mine), and will be used by folks who might have a version 1.0 board or a version 1.1 board. It caught me off guard that there was a change between the boards, and I want to be able to use the same config across different hardware revisions.

What I would up doing was cutting the MS1 jumper on the new (v1.1) board to make it 1/16 microstepping as well. It’s not written up in any of the pages I came across, but it is (sort of) on the schematic. The schematic in the latest, master branch on the Smoothie Github (both PDF & .sch files) still shows the A4982 drivers, although the BOM doesn’t. And curiously, the schematic also does include an MS3 jumper, despite the fact that the A4982s don’t have an MS3 pin. Presumably, this works out when using the A5984s.

Summary:

  • board working with existing config b/c I cut the MS1 jumper.
  • Docs are still a bit out of sync (schematic shows A4982, BOM and actual hardware use A5984).

As always, thanks for your quick replies and excellent hardware!