First post after spending a couple of days reading all the posts. I am excited to build my controller and have had e few ideas for features that would really make this a full feature unit.
Since the idea of using a Atmega16 is being kicked around how about lets think about putting an H-Bridge into this so we can go in reverse without a transmission. Not everyone would need to build that part of the circuit if they only wanted forward rotation.
The following old diagram that I have found many times over the years uses N and P channel Mosfets for simplicity.
The Using MOSFETS Website: H-bridge using P and N channel FETs
Here is an excellent simple explanation of how an H-bridge works.
http://www.barello.net/Papers/H-Bridge.pdf
Even on a light weight Metro that would allow us to remove the transmission and just keep the differential and re-case it. That would shave about 30 pounds off the package. For heavier Units this could be a very significant gain.
An added benefit to this setup is the possibility to regen during breaking. Want to slow down? throw on the P- channel at a low rate. Kinda like a a Jake brake on a semi-tractor. Not full braking just a couple of hundred amps at the most.
Just some thoughts on some features I would like to see. I think all the work that had been done on here is fantastic and I can see how this could be a really great controller when completely finished.