Parallel Port -> 4-bit DAC driven monolothic chopper controller

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29 May 2019 14:12 #135271 by fungus
Hi Andy!

I got it semi-working. Had a little hardware hangup because I hadn't pulled up the DAC REF line. After that, I got motion!

The motor is very silent now, but the motion is quite irregular, especially in one direction. There's a bit of funkiness going on that I can't capture through HALSCOPE, so I'm going to set up my big boy scope on it and see what is going on at the hardware level. This does not appear to be a tuning issue (although the tuning is not correct).

I'm spread across 2 houses and my garage right now, so at no point do I have access to all my tools.

I'm very interested in how this turns out, as I intend to tinker with my own designs of velocity-mode amplifiers. This would enable simple & cheap analog communication with my designs!

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29 May 2019 14:25 #135272 by andypugh

fungus wrote: I'm very interested in how this turns out, as I intend to tinker with my own designs of velocity-mode amplifiers. !


You could do that, or you could join in with the STMBL project ;-)

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29 May 2019 14:46 #135274 by fungus
I had a lot of hope for STMBL, and I still do. I lost touch with it during the shortage/EOL of the MCU though. Have they overcome this yet?

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29 May 2019 14:49 #135275 by andypugh

fungus wrote: I had a lot of hope for STMBL, and I still do. I lost touch with it during the shortage/EOL of the MCU though. Have they overcome this yet?


The problem is not the MCU but the power bridge.
As far as I know there is no replacement design yet, but it is being worked on.

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29 May 2019 17:10 #135305 by fungus
Wow, that's a different component... Not sure how I got confused there. I'll check back in on it.

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07 Jun 2019 01:18 #136146 by fungus
I finally got a chance to hook up my scope and see what's going on. One direction is pretty smooth, but the other has ~4Hz period between port writes.

I'm not going to spend too much time digging into it, because as Andy said... This would be a lot better off as a separate HAL component.

I won't say that my priorities will not change in the coming year, but I would love to revisit this as I work my way through classes. It'd be a great intro to HAL components.

The following snips show the labeled channels:
DS1Z_QuickPrint3 was a slow jog in +X, it was smooth.
DS1Z_QuickPrint4 was a slow jog in -X, it was rough (approx 4Hz on the DIR pin).
DS1Z_QuickPrint1 was a fast jog in +X, it was a bit rough.
DS1Z_QuickPrint2 was a fast jog in -X, it was very smooth.

Bear in mind, this is still generating PWM at this point. I'm using the PWM component for direction.
Attachments:

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07 Jun 2019 02:57 #136161 by fungus
Andy, it looks like the IRC for STMBL hasn't been active in a while; the github repo hasn't had a hardware commit in a while. Do you know if the original maintainers/creators are actively working on the project?
Not that I have a whole lot of experience, but I would like to see it stay active.

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10 Jun 2019 16:20 #136485 by andypugh

fungus wrote: Andy, it looks like the IRC for STMBL hasn't been active in a while; the github repo hasn't had a hardware commit in a while. Do you know if the original maintainers/creators are actively working on the project?


Yes, very much so.

You might be looking in the wrong place:
gitter.im/rene-dev/stmbl

Have a look at the message from 1st June.

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17 Jun 2019 02:08 #137084 by fungus
Thank you Andy. I signed up there, and I hope to participate in the testing of the new drives!

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