alec_t well, yes an no, at the beginning the intention is to make something like this:
But squeezing a power regulation, rs232 communication, a uC, the hbridge circuit, current limiting, 10 leds and about 12 inputs and outputs in a 9x15cm perfboard you end up with a messy circuit (specially when you find you made 3-4 mistakes that you'll fix).
Then if you consider the above diagram a star grounding, then I think yes, this is pretty much how it looks like.
I tried triggering the h-bridge with a 555 circuit (the uC is separated from the hbridge but still sharing the ground) the uC is still being reset then that way I guess an optocoupler wouldn't help much, I don't have one, but i think I'll try an optical switch instead just to be sure. Note that the first hbridge circuit (no transistors) didn't reset the uC working in the same conditions.
ronv that looks to be quiet complicated, I used some big capacitors between the supplies' leads and a small ceramic capacitor between the motor leads, but nothing improves.