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Date:	Tue, 21 Apr 2015 20:21:53 +0200 (CEST)
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From:	gedau AT igor2 DOT repo DOT hu
Subject:	Re: [geda-user] Stepper driver issues
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On Tue, 21 Apr 2015, Rob Butts wrote:

>I know this is a geda list and this question=C2=A0should be=C2=A0asked som=
ewhere else
>but I'm homebound, I haven't worked with other engineers in years and this
>is the only place (and best place) I know of to hash a problem out with
>other engineers.=C2=A0 If anyone knows of a better forum please advise.
>
>I have a nema 23 stepper motor (to turn a trolling motor for a kayak)=C2=
=A0I want
>to drive in bipolar 2 phase.=C2=A0 I'm using a Microchip 16f1939 with the=
=C2=A0On
>Semiconductor STK682 stepper motor driver.=C2=A0

<snip>

>Suggestions?=C2=A0 Advice?

Random things I'd check:

Put scope on the output of stk682, with and without the stepper=20
attached; check if it's trying to drive it or not; maybe try some 47..470=
=20
ohm resistors instead of each stepper coil to show give it some dummy load

If it doesn't produce any output without the stepper attached, check:

- whether all the external caps/resistors are in place, as shown on the=20
application circuit diagram of the stk datasheet. I am not 100% sure but I=
=20
think you'd need to be able to measure the oscillation on the OSC pin

- the enable pin

- the fdt pin

- whether you are within the spec, e.g. VM has to be at least 9V,=20
there's some overcurrent protection too so if your steppers would take too=
=20
much current the circuit may shut down

If it does produce the output without the motors connected but not with=20
the motors connected, then perhaps either stk682 or the PSU is too weak=20
to drive the motors.

If it does produce the output in both cases and the motors still don't=20
move, it may be that the chopping freq and/or your clk are too high.

Regards,

Igor2
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