karenhornby, I would suggest using an 18F2620 as there are enough pins to do what you want as well as 2 CCP modules a voltage reference, comparator and you can run it at 40Mhz. if necessary. I have used these parts for many products over the last year and 1/2 and have had great success. If you are planning on laying out a pc board it will give you some extra pins to use in the future... It also has 4 timers and enhanced capture/compare for use with an H bridge later on if needed...

Dave Purola,
N8NTA