Setting up lathe speed with 7i76 digital pot

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10 May 2019 11:01 #133339 by Stigoe
I mapped actual speed versus commanded speed (only low gear for now) and linearity is actually spot on (checked with an Excel-graph), just a wrong slope.


I'm not sure how to implement the lincurve into the logic.

I've set up all the lincurve x- and y-values and I've tried to follow the lead from the other topic using lincurve, but then I get lost as gearchange has been removed, but it looks like he is still using two speeds.

Before I started messing with lincurve, I have
net spindle-speed-scale motion.speed-out => scale.0.in
net spindle-speed-raw motion.spindle-speed-out-abs gearchange.0.speed-in
net spindle-speed gearchange.0.speed-out hm2_5i25.0.7i76.0.0.spinout

Since I have a two-speed, I guess I need to get the output from the gearchange.0 into lincurve before it's sent to the digital pot? So would the correct sequence be gearchange.0.out -> lincurve.0.in -> lincurve.0.out -> .spinout?

Br,
Stig
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10 May 2019 13:04 #133350 by andypugh
Maybe:
Spindle.speed.out => lincurve.slow.X
Spindle.speed.out => lincurve.fast.X

Lincurve.slow.Y => mux.0.in0
Lincurve.fast.Y => mux.0.in1

Mux.0.out => 7i76.spinout

Gear-switch => mux.0.sel

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10 May 2019 19:33 #133400 by Stigoe
Thanks, Andy.

This seems to work, but I had to change several things. I had to use named lincurves, I had to use .in and .out instead of x and y and I had to use signal names to assign the various signals. But limited testing looks promising... :-) Doing it this way, I think I may be able to remove the whole gearchange signal as well.

Br,
Stig

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10 May 2019 19:38 #133401 by andypugh
Yes, you don’t need gearvhange with this setup.

And I was on a bus to the airport on my phone when I typed it and didn’t have the docs to hand for actual pin names.

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11 May 2019 07:16 #133432 by Stigoe
Again, thanks, Andy!.

I may need it for the speed settings (max/min) in the system and for selecting low or high, but I don't need to send the speed through it.

No worries. I did struggle somewhat, but I would have struggled a lot more without your help... :-)

Have a nice flight wherever you're going. Early tomorrow morning, I will be in a taxi on my way to the airport...

Br,
Stig

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