>How do you control your motors?  I am building a similar system.

The PWM outputs through optoisolators.

>I also use PWM to control the speed of my motor, but it makes lot
>of noise.  What is your PWM frequency?

I had a lot of high-frequency noise in my first attempt so I turned
down the PWM frequency.  I wish I knew what it is!  I am using 1:4
duty cycle(?) (CCP1CON & CCP2CON =3D 0x0C), PR2=3D0xFF, and
T2CON=3D0x06.  My frequency meter says it's about 236 Hz, but
I don't get the same answer by working the equations.

>Any sensors for your robot?  I have total of 8 IR sensor (one of each side
>and one at each corner), but I don't know how to write the code so that
>every possible combination of detection is covered.  Any tips?

Just 2 forward IRPDs looking down to detect maze lines (for now).
Perhaps a state engine will work better with more inputs, I have an
article I want to read about SE's ... you might find it on their website...
Embedded Systems Programming magazine, December 2000.

Let me know what you learn!

- Bri

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