How to read current in a curcuit?

[Dingo]

I was wondering if anyone knew of a curcuit layout that could feed the current drawn by a DC Motor into a PIC?

Basically I want to have a a cutout if the motor approaches anything near stall current.

Any ideas?

[Bones]

Hi,
What you will need is called a H-Bridge motor driver.
What voltage is the motor and current draw and stall current. Proberly a themal fuse for the overload cause they auto reset.
Get us those details and I'll check. Sometimes it is better to get an off the shelf one cause it is designed for it

[Dingo]

At the moment I'm just using those really small toy motors (you know the ones.....(see tracks under projects if not) but these are just prototypes - later I'll use more serious motors. So basically 3-6 volt, Stall at 1.5 amps approx.

Currently I'm driving them via a L293D. I could just put a 1 amp fuse in - that is a good idea.

But is there a way the get a reading of the current - I mean is there an "Ammeter IC" or anything like that?

I assume Ohm's Law plays a part

[bender]

www.rev-ed.co.uk/picaxe/forum/Topic.asp?topic_id=1397&forum_id=11&Topic_Title=Ammeter%252C%2BAH%2Bmeter&forum_title=No+new+posts+please%21
have a read of this

[ZapBrannigan]

We made a current limited power supply as a project at uni. It followed the same kind of principle as the PICAXE project that Bender linked to.
However we did it slightly different. We used an op-amp in a comparitor configuration, to do the comparison. The output from the op amp would then (if current matching our configured maximum) draw the output of the power supply to ground.