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Originally Posted by MikeDubreuil
...I have the function generator directly connected to the mini-RC. I am verifying the signal on an oscilloscope. Unfortunately, I just can't seem to generate interrupts unless I am removing the PWM cable from the RC. Which makes me believe the software is working at least half correctly. I think it has something to do with the internal pull-up resistor inside the RC. Can anyone shed some light on this? Thanks.
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OK, I'm going to make a SWAG at this. After re-reading your description, this is what I think my be happening. When a system, the mini-rc in this case, has a pull up resistor on it, it's signal will always be high. ( I can hear you saying "duhhh, I know that") To pull that input low, you need to ground the input, or at least pull it down low enough for the circuit to detect it as low. But, her comes the SWAG, the ground level needs to be referenced to the same ground used on the system with the pull up, got it? My guess is that the signal generator is not tied to the ground of the mini-rc, and therefore, the mini-rc if floating and not able to see the 0vdc portion of the square wave. I hope you are running the mini-rc from a battery, if so, just connect a wire from the ground of the signal generator to the negative input of the battery driving the mini-rc. The signal generator might/should have a ground connector on the front of it for situations just like this, or at least in easy access to the front. But, if you are running the mini-rc from a power supply, be careful connecting the two together, if the ground of the signal generator is slightly different from the ground of the power supply you could fry stuff quick. Once you like the magic smoke out, the mirrors don't work
... just kidding. Measure the potential between the two grounds. If you see just a couple millivolts, you should be cool.