[KenWittlief]

the IR beacons used have a 40Khz carrier frequency - there are many different frequencies used by IR links, so unless you have looked into it, the chances are your PDA is not on 40Khz - which would explain the reduced range compaired to the sensors FIRST gave us.

We used the IR beacons and had no problem, but only look for them 90° off the sides of our bot - so we dont need to see them until we are passing it about 3 to 8 feet away.

we were at pittsburgh and they seemed to work fine for us.

I made a beacon using a PIC chip and the circuit provided by FIRST - this allows us to use the EDU bot as an IR receiver - I wish I understood your problem better at pittsburgh - we could have verified the beacon operation with our EDU RC

but if FIRST says they were working I would think they had something similar to check them with - I would seriously consider checking your code - are you using the default stuff from innovationfirst? or did you make changes to it.

interrupts can be very tricky, and when something is not right with them intermittant operation is one of the symptoms

we are not using interrupts - only the INT1 and INT2 flags, polled from the main loop to see if the pin saw a transistion, then we clear them in SW - no interrupts are enabled in our code.