Uno with SN754410 and bipolar stepper - motor jerking

I've tried all wire combinations - 12v gel battery as motor power. Exactly the schematic shown on this site. Perhaps my uno or the SN is blown?

Please garthn, keep the discussion in one thread, that is easier for all of us and for yourself. Just use reply instead of new topic.

Um - that doesn't work. I posted my original more than three hours ago with no reply. So my subject line was not good because I had responses to subsequent posts. Different forums have different practises - if I am abusing this one then I apologize. I find for instance on Oracle sites I must potentially post several times until the topic registers with someone else

The problem is that you are not asking a good question. You provide little actual detail, no links to what you have tried, no softwar, no photo of what you have put together. What you put was inadiquite to attempt a reply.

Clearly you are doing something wrong but you don't give any one a chance to spot what.

That was not helpful. All you had to do was read my question properly - which you clearly did not do. So let me spell it out - again.

I am using
a) a Uno R3
b) an SN754410NE
c) a four wire bipolar stepper (tried two, EM257 and EM258)
d) a 12v gel battery
e) the schematic exactly as on this website <==== read that again please

I’m not expecting someone to inspect a photo and tell me my wiring doesn’t match the schematic - it does. I could video the jerking or lack of motion of the motor - but why? it might mean something to an expert - but if everything is correct it would be a meaningless exercise.

I'm actually mystified by your post - if a website supporting something as popular as the Arduino publishes a method of using the product, and the method is followed and doesn't work, why are further details required? that actually stuns me. :~

The only two factors outside the known equation are the motors - and the power source. And I detailed both?

That was not helpful

You have to ask yourself why your posts remain unanswered for so long. Most posts get answered here very quickly, if yours has not, that has to tell you something about the quality of what you are posting, or the obscurity of the request. Or, the fact that I think you favor, that everyone is deliberately ignoring you because of some vendetta we collectively have against you.

the schematic exactly as on this website <==== read that again please

Yes read it twice and I would ask again:-
What web site
The web is a big place what web page are you talking about, please provide a link?

I’m not expecting someone to inspect a photo and tell me my wiring doesn’t match the schematic - it does.

A bit arrogant that isn’t it. There is always something you can miss. I have been doing electronics for over 40 years and sometimes I can miss things for days. The phrase is “you can’t mark your own homework”.

What form of answer are you expecting here? Is it that the web page is wrong? It might be but as we don’t know what one it is we can’t check. Is it that you must have blown up a chip? Is it that your software doesn’t match the way you have wired it up?
With the information you have given it is imposable to check these things.

Just a shot in the dark, have you tried swapping the wires of the motor around? That sometimes causes a problem. Also you could try slowing things down, you might be going too fast for the motor.

It is me that is grumpy right now - for the reason at the bottom of this

I would have thought "this website" makes it clear that I am referring to arduino.cc - that thing in the address line of your browser is called a URL and it contains that.

As for the wiring matching the schematic - it is identical. This is not some difficult homework. I'm not expecting someone else to have to check that "a is connected to b connected to c". I checked my own wiring connections with an ohm meter - except those finally coming off the board for the motor.

And I have subsequently found that my breadboard was not feeding some pins - I didn't expect that to be faulty. I have also been given a very useful tip, use an old PC speaker to see if current is being supplied to the wires going to the motor etc. The pulses are clearly audible as clicks - and the SN754410 output pins click louder, showing current amplification is working. Also - one of the HWM pins I was using seemed to be faulty - I didn't try to make sure, I just switched to another one.

I switched motor wires while testing - into all possible combinations, not just switching two around.

And now - I seem to have blown my atmega chip - I've posted (and had plenty replies) that in the troubleshooting section. Resetting does not cause LED 13 to blink.

I would have thought "this website" makes it clear that I am referring to arduino.cc -

Yes but it is a big website with several references to that chip, is a link so hard?