Review of a small motor controller schematic.

[Gdeaver]

The motor controller chip does not have current monitoring. It's ashame to have all that CPU power and nothing for it to measure. You might want to consider the Freescale MC33887. It has current monitoring and some additional protections. How about some reverse polarity protection? A P or N channel FET can provide this with the cost of a little more resistance in the current path. If you do use the chip you chose, put a heat sink on it You can use the CAN buss but, allot of other motor controllers use RS485. You could duplicate the command structure. The problem with motor controllers is that there is a good chance of frying one when proto typing. You could separate the controller parts from the drive. Hope fully one board will survive instead of frying the whole thing . After you get it working the boards could be stacked.