Floating Grounds?

Hi all,

So I've been working on a project that requires me to run a servo and a motor at the same time. I've run into some problems that were more along the programming side and I posted those at this page:

I think those problems have been solved as I got some very good help but now my problems seem to be hardware. Supposedly, the software towards the end of that thread works and when I scoped a new board I got today (my old one didn't), it works. But when I try to physically run the two motors simultaneously, it doesn't work. When I turn off the power supply for the motor, the servo starts working. When I turn off the the power supply for the the servo and turn the motor supply on, the motor starts working. Basically, only one of the two will run at the same time (one complete circuit at a time) but all signs indicate that they should be able to both run, from scoping.

So I'm wondering if there's something that's interfering with the two sub circuits. Currently, my board is very clustered because I have a ton of other sub-circuits on there two. I have everything grounded to the same arduino ground pin but because I'm forced to use a tiny breadboard for this project, I had to make multiple ground 'buses' from this pin using wires because there aren't power buses for this breadboard (if this is a problem, I think I may just take the hit for using a better breadboard). So I'm a little curious if my two motors might not be working because the separate grounds are 'floating' relative to each other and not really the same ground? Obviously, this would be hard to tell conclusively unless I tried it out but I just want to know if it were a plausible possibility that adding wires to ground would create significantly different voltages (for ground), before I take everything apart. (And if so, what suggestions you would have for the future?)

I'd suggest you start your post again. The first thing you do in this thread is point us to another thread. Looking through THAT thread I find NO schematic and NO code.

So forgetting this unhappy diversion I then continue reading through THIS post to find

I think those problems have been solved as I got some very good help but now my problems seem to be hardware. Supposedly, the software towards the end of that thread works

So back I go. looking for the elusive software "towards the end of that thread" Nope, still can't find it. Furthermore I can't even work out which of the users in that other thread is you!

I get the impression you're having problems with your hardware not behaving as you'd like but I can't even guess how you have it setup or what code you're running.

Try to post something that gives a schematic of what you have and the code that you're running and a detailed description of the problem. When doing so, write it as if you're addressing someone you've never spoken to about your project before.

because I have a ton of other sub-circuits on there two.

What's a sub-circuit?

[quote author=Nick Gammon link=msg=2073244 date=1422949151]
What's a sub-circuit?
[/quote]Well they're sure not super :wink:

Hi,

Can you please post a copy of your sketch, using code tags?
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png or pdf?

Tom… :slight_smile:
My step daughter wonders why I have a little text file on my desktop with various non connected sentences in it.
How do I explain.

You need one of these.

Hi,nice but do you have enough keys?

Tom..... :slight_smile:

Good question. As the post mentions I added a "shift" key to double the number of messages you could send. Then I had to add another switch to get it to automatically add "url" tags around links since the forum doesn't do it any more. It had to be an option because if I actually want to follow the link (in my web browser) the URL tag is not required.