PICStep Firmware V1.01

[santiniuk]

Well looks like Alan has been busy in the background.

From his site :-

upgrading the PICStep firmware to utilise a "High Torque" stepping wave instead of the Sin/Cos wave I'm currently using.

Can anyone explain a bit more about this. Quite interested in how it works and what type of increase can be seen.

Thanks

[mk2lehe]

Imagine a sine wave feeding one coil in stepper. Imagine another wave (same but delayed 90 deg) feeding the other coil. That's how Alan's 4.0 works.

There isn't anything wrong doing so, but there's a trick getting a bit more torque in the areas where none of the coils are fully energized. I read about it in an application note.

The trick is having both coils at +100%, and then adjust current on first coil down to -100%. Then adjust second coil current to -100%. Then first goes up to +100%, and after that second goes up to +100%. We're now back to where we started.

Total current increase at 45 and 225 degrees is 20.7% (sqrt(2)/2). I suppose torque is raised equally, 20.7%, at these two points.

Note: There's no such thing as a free lunch. The extra torque is more current, which means heating up stepper a little (~7% more dissipated heat if I did my math correctly).

Henrik

[Garfield2]

Originally Posted by santiniuk Can anyone explain a bit more about this. Quite interested in how it works and what type of increase can be seen.

I think Henrik explained it better than I could (well he oughta as he's the one who found out about it. ).

I must admit however, I started setting up my workbench for PICStep development (which envolved packing down my PICServo setup so I have some bench space to work on) and I was struck with an idea that fixes the problem I'm having with PICServo's firmware. So to cut a long story short, I've still not packed away PICServo and started on the new PICStep firmware...

The new firmware won't take long, and now I feel guilty for not doing it so I'll try and get started on it today sometime.

Cheers,
Alan.

[santiniuk]

Thanks Henrik for the explanation.

Another improvement for the Picstep design. Keep it going Alan.

I know your busy with picservo but when you have chance how about a little update. Just enough to make us drool

Cheers

[santiniuk]

Just catching up with the posts on here Alan. Any progress reports on the firmware ?

Just interested really as I was more than chuffed with the original one.

Dare I mention Picservo ? Hows that one going too ?

Cheers

[Garfield2]

Originally Posted by santiniuk Just catching up with the posts on here Alan. Any progress reports on the firmware ? Just interested really as I was more than chuffed with the original one.

Ahh yes, that elusive thing that I can never find; spare time!

Currently, I'm re-implementing my stock control and processing system at work and that's eating all my daylight hours. And to be honest I'm so buggered at night I can barely turn on my computer to read my emails! I promise I'll try and find time to implement the changes, it's really is lazy of me as it should only take 10 minutes to make the changes.

Originally Posted by santiniuk Dare I mention Picservo ? Hows that one going too ?

ARGRHGRHGRH< cough >< cough >GHGHHGHHHG< choke >< splutter >< pant >GHGH!!

It's actually coming along *really* well. When I've found time to work on it, I've implemented a pretty standard binary protocol that will allow you to adjust the servo controller parameters via RS232 and a simple .NET application (and a GTK based one for linux!). The software will allow you to monitor the controllers operation while you drive it via step/dir pulses via TurboCNC or Mach2 or whatever so you can adjust the PID loop to within a very small tolerance.

All good.

So what have you been upto, I've heard no updates from you and your machine either < poke >< poke >!

Cheers,
Alan.

[MrBean]

Just found this thread. New firmware Oooooh. Nice one Alan. A bit more torque is always welcome.

Regards Terry.....

[Garfield2]

Originally Posted by MrBean Just found this thread. New firmware Oooooh. Nice one Alan. A bit more torque is always welcome.

Done! Check out my site for the updates.

Cheers,
Alan.