Let's Make Robots!

Problems with axe 08m and l293n

Hi LMR!

I have a teeny problem - I'm playing with stepper motors for my next robot, the plan is to have an 18M2 sending serial packets to a pair of 08M2s which each will control one stepper, to save outputs on the 18.

My problem is this, when I have the 18 running into the L293 driver the motor runs perfectly, but when I use an 08 nothing happens and it gets hot (I fear the magic smoke)...

As far as a setup goes, I've coils 1,2,3,4 running (via the L293) from outs 0,1,2,4 on the chip in that order, both Vccs and the picaxe running from the same 5v supply, a unipolar stepper motor, I think that's everything...

Here's a photo of the board in the state it is when things get hot:

Any and all help gratefully recieved :)

Mike

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Hi, sorry about the picture, my good camera's the wrong side of 300 miles away :( I guess it made sense to me only cos I put it together! :D

I separated the two chips onto different boards with jumpers between and that seemed to cure the heating problem, but now I have another, but I'll put that up as a seperate topic cos it seems wierder...

Thanks for the help guys!

I already decided I was not going to try and sort out the wiring. The fuzziness makes my brain fuzzy...  ha ha

Also, how about a schematic for how you intend it to be wired so we can compare.

The L293 driver IC will pull the same drive current no matter which one it is hooked to, so if everything is wired right, there is no reason there should be any difference between the 18M2 and the 08M2 as far as what you can drive with them.  As far as Picaxe μControllers, this is a "no smoking" zone.

Wow, that picture is blurry. Can you post a better one?

At least tell us if the notch on each chip is facing to the left or the right so we know what pins are what. I'm trying to sort through all the connections, but it is making my eyes hurt.

When you say 'nothing happens', can you be more specific? Are you able to download code to the 08m with this circuit? Is the chip still responding or is it fried? Does the 08m stay cool if you clear the program so it is not driving the circuit?

Oh! I think I know what it might be.

The 08m shares the serial out for programming with digital out 0. If you are trying to communicate to the 08m serially at the same time it is trying to send output to digital out 0, it may not like it.