How to use multiple L293D drivers

Hi,

This is no doubt a slightly dumb question but despite a lot of googling I can't find quite what I'm after and I'm a little scared of frying my arduino...

I want to control 2 stepper motors from my arduino. My understanding (from looking at the circuit diagrams on Tom Igoe's site) is that I'll need an L293D driver per stepper motor. I've struggled to find any information on how to wire up multiple L293Ds.

Obviously I'll be connecting each one to different set of output pins on the arduino but power-wise, am I connecting them in parallel ( their Vcc1 pins in parallel to the +5V pin and their Vcc2 pins in parallel to the ext power pin)?

Also, this is probably a terribly naieve question but how much current can be grounded through the ardiuino ground pin and does it make a difference whether your power source is usb or an external DC supply?

Thanks for any help you can give and be nice if I've completely missed the point!

I connecting them in parallel ( their Vcc1 pins in parallel to the +5V pin and their Vcc2 pins in parallel to the ext power pin)?

Yes.

You have to connect the grounds together to give them a common reference.

You shouldn’t run the motors off the USB supplied current.

Thanks for the reply.

You have to connect the grounds together to give them a common reference.

Sorry, let me just check I've got it straight. I connect the +ve leads as I mentioned (as I understand it the Vcc1 pin is logical power and the Vcc2 receives the motor power and then the ground pins for both drivers need to go to the ground pin on the arduino. Is that right?

and then the ground pins for both drivers need to go to the ground pin on the arduino. Is that right?

Correct.

Brilliant! Finally I feel confident enough to try to make things move :)

Cheers