Thank you everyone for your reply.  I just want to
clarify that the L298 is a DUAL Full-Bridge driver. 
Driving 2 of them means I need 4 PWM channels.  All
channels can be at the same frequency, as long as I
can vary the duty cyle for each channels.  I think I
am going to use the PIC18F4431 since it also have a
Quadrature Encoder Interface (QEI).  Too bad it has
only one QEI.  I need two!

Is the frequency for the PWM matter?  Is there a "rule
of thump" on what frequency is good?  Since I am
running the PIC at 40Mhz, it looks like 2.4Khz is the
slowest it will go.
Regards,

--- Gerhard Fiedler <lists@connectionbrazil.com>
wrote:

> Alan B. Pearce wrote:
> 
> >> Is there any other PIC that has 4 (or more)
> independent PWM channels? 
> > 
> > I think some of the 18F may also, but I believe
> you can only use these
> > for motor driving, and not as independent
> channels. 
> 
> There are a number of PICs with 4 and more
> semi-independent PWM channels.
> Look for numbers of (E)CCP modules. They are
> independent in that you can
> run every (E)CCP module with a different duty cycle,
> but they are not fully
> independent in the selection of PWM frequencies --
> you only have one or at
> most two different frequencies. (The 18F6722 is one
> with 5 (E)CCP channels
> that can be driven from two different timer sets.)
> 
> But as others have said before, for two motors you
> only need two PWM
> channels, a few standard digital outputs (for
> direction and possibly
> breaking) and a bit of glue logic. 
> 
> Gerhard
> 
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