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Topic: SLA7026 - stepper driver (Read 2143 times) previous topic - next topic

Does anyone have any experience with the SLA7026M unipolar stepper motor driver working with Arduino? I'm using a 2A, 6 wire unipolar stepper motor, and i'm supplying it with +12V. I got it working earlier but now the motor doesn't want to rotate properly - it just steps backwards and forwards!
Could anyone help me out with schematics they may have used in the past?

Cheers,

Michael

Grumpy_Mike

Post what you have got and we will tell you how to fix it. If it did work you probably have them wires mixed up.

#2
Apr 06, 2011, 01:06 am Last Edit: Apr 06, 2011, 01:14 am by michaelb01 Reason: 1
Thanks for the reply Mike. Here is a quick Eagle schematic I made (my first post so hopefully this will link properly?) - http://www.flickr.com/photos/61504193@N08/5593139631/

I assume it is something stupid like confused wires but I've been over it so many times and still no success!

The input pins connect to 4 Arduino pins. The two common wires of the stepper are connected to +12V. The off-time delay pins don't seem to have any effect if they're connected or not.

I guess you need to look at the SLA7026M datasheet really (don't know how I can link that), but i'm driving it in Full Step operation according to the datasheet, which is:

Sequence         0       1       2       3       0
Input A            H       L       L       H       H
Input notA       L       H       H       L       L
Input B            H      H      L        L       H
Input notB       L       L       H       H       L

Hope this helps?


Does anyone have any suggestions?

Khalid

I have used SLA062M based unipolar stepper driver.. you just to give it pulses through Arduino using any 2 pins. One for direction and one for steps. the ground of SLA should be common to Arduino.
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I'm confused, I only need a total of 2 Arduino pins to control the stepper? I had hooked up 4 pins from the Arduino and connected the 4 output pins from the SLA7026 to the motor (as in my circuit diagram). So how do the motor wires connect to the driver?

Regards,

Michael

With my current circuit (the one at the top of the page) i've hooked up four LED's on the outputs to simulate the stepper motor coils. At the moment, outputs 3 and 4 are constantly on, and outputs 1 & 2 flash on/off alternately - they are on for 3/4 of the logic sequence I am sending the driver inputs.

Grumpy_Mike

I noticed from the circuit you posted that you have not got anything connected to the reference inputs. The data sheet shows this being fed by a potential divider and AC coupled to the sense pins. That could explain why it is not working like you expected.

MarkT

#8
Apr 06, 2011, 06:28 pm Last Edit: Apr 06, 2011, 06:30 pm by MarkT Reason: 1
Quote
I have used SLA062M based unipolar stepper driver.. you just to give it pulses through Arduino using any 2 pins. One for direction and one for steps. the ground of SLA should be common to Arduino.


All very interesting but that's a totally different chip!

As for the SLA7026M then what Grumpy Mike says applies....


Edit:  There is no SLA062M!!!  There is an SLA7062M, but that's still a different chip from the SLA7026M!
[ I won't respond to messages, use the forum please ]

I connected up the reference pins as shown in the datasheet - NPV's were 680 ohms on the top (to +5V) and 100 on the bottom (to ground), giving me 0.6V on the reference pins. This had no effect on the output at all. I'm starting to think that the chip is faulty since outputs B and notB are constantly on (these are controlled by half of the device) and any changes I make on the reference pins has no effect on these outputs...

MarkT

What do you mean by 'on' - all the output transistors will switch off if the Vref is below Vsense - making the outputs high.  The outputs are "on" if they pull low.  Internal logic prevents both B and notB outputs being LOW (active) simulataneously.
[ I won't respond to messages, use the forum please ]

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