X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient: geda-user AT delorie DOT com
Date: Sun, 28 Jun 2015 19:12:05 +0200
From: Bernd Walter <ticso AT cicely7 DOT cicely DOT de>
To: "Rob Butts (r DOT butts2 AT gmail DOT com)" <geda-user AT delorie DOT com>
Subject: Re: [geda-user] Stepper driver issues
Message-ID: <20150628171205.GB94280@cicely7.cicely.de>
References: <20150422161012 DOT GA42355 AT cicely7 DOT cicely DOT de> <CALSZ9grVrYv0BS3_y7ez8VXBwTXxAMazWB6gdCuLUe2+6Uzzyw AT mail DOT gmail DOT com> <CALSZ9gq73RBxHV5LPe7pQWNO3kK7EPXaRiN0U7zFBV9BsQX78w AT mail DOT gmail DOT com> <55395CD0 DOT 70107 AT m0n5t3r DOT info> <20150423214501 DOT GD47936 AT cicely7 DOT cicely DOT de> <CALSZ9gqAPj6h2Z_gLvHTBdL-cnQ6p_juTonjE0e+oDAaRy7KTQ AT mail DOT gmail DOT com> <55530929 DOT 2070301 AT gmail DOT com> <CALSZ9grqsRc+U5p=LeQpzBU6_c6tWg-VrDYEqav99K_1L1P=2Q AT mail DOT gmail DOT com> <5555971C DOT 8000902 AT gmail DOT com> <CALSZ9gqtmaetZs7rHrx_sTrc1vqKkMMvDhPf0P9vs4EmuC9Q3w AT mail DOT gmail DOT com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CALSZ9gqtmaetZs7rHrx_sTrc1vqKkMMvDhPf0P9vs4EmuC9Q3w@mail.gmail.com>
X-Operating-System: FreeBSD cicely7.cicely.de 7.0-STABLE i386
User-Agent: Mutt/1.5.11
X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED=-1,BAYES_00=-1.9,T_RP_MATCHES_RCVD=-0.01 autolearn=ham version=3.3.0
X-Spam-Checker-Version: SpamAssassin 3.3.0 (2010-01-18) on spamd.cicely.de
Reply-To: geda-user AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: geda-user AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

On Sun, Jun 28, 2015 at 12:43:58PM -0400, Rob Butts (r DOT butts2 AT gmail DOT com) wrote:
> Sorry to keep hammering this stepper driver issue on the geda board but my
> collaboration options are very limited.
> 
> This kayak steering via a nema 23 stepper is driving me BONKERS!  I had it
> working prior to last summer but then spent 4 months in the hospital
> critical, got out, worked on the shifting code, now the steering isn't
> working and I can't figure out for the life of me what changed!
> 
> To sum up: I am using the Pololu DRV8825 stepper driver that I set up on a
> bread board with a microchip pic16f1937.  I have verified with an usb logic
> analyzer that all the control signals to the drv8825 are correctly
> programmed and that the output A+, A-, B+ and B- signals are what they are
> supposed to be without the stepper connected.
> 
> I then connected a new stepper and it made a soft whining sound but did not
> turn.  I am certain it is wired correctly.  Now the stepper does not appear
> to work.
> 
> I am sure I ordered a 12V 2.0 A stepper but looking at the motor tag it
> says 1.2V and 2A which probably explains why it didn't work and is now not
> working.

That's perfectly Ok.
A stepper has coils, you can apply up to 12V to charge the coils to their
current.
The driver is limiting the current, so once charged the voltage drops, in
this case to 1.2V - perfect would be 0V, but unless your coil is made
of a super conductor it has a resistense higher than 0 Ohm.

There are a few things to care about.
The voltage supply to the driver must be stable, which also means that long
cabeling can be an issue.
Otherwise, since you already got it running once, I assume you already know
about changing coil currents for rotation.
I never used the DRV8825, some drivers expect step direction signals, while
others expect you to setup coil currents.
The DRV8825 likely is a step direction one, so you need to apply step pulses.
"a soft whining sound" can mean it is just standing still without step signals,
or step signals are to fast for the motor to start rotating.
It can also mean instable power supply.
At least it clearly is driving the motor somehow.

> Does anyone know of a good source for a nema 23 stepper motor?  The drv8825
> is rated for 2A and my kayak trolling motor is not difficult to turn so I
> don't believe it needs to be high holding torque.

-- 
B.Walter <bernd AT bwct DOT de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.