Pulsein issues...

I am using a pulsin to read RC signals. I am using a 18F2220. It works fine with a HiTec Radio hooked up to it. I can't get it to work with a Futuba. I put the futuba and and hitec on the scope, they are exactly the same width, the only difference is the futuba is 3V peak, and the HiTec is 3.3. Theu are both above the threshold, right? It will work with the Futaba on port C3, A6, A7, and A5, not on port C2, C1, C0. I really need it to work on C2, C1, and C0, I already have board made and need to read 7 channels. It worked fine with the HiTec, but now I'm struggling with the Futuba.

Thanks

Hi, Payne

Do not use a schmitt trigger input or build a level adapter ...

Alain

OK. I jumpered to some spare TTL inputs and that seemed to fix it. It works pretty reliable on one of the Schmitt triggers. What if I just power the PIC with 3.3V, will that fix the issue?

I'd forgotten to suggest you !!!

Alain

Hi,
Are you using a pullup resistor on the input? the upper voltage doesn't really matter 3v, 3.3v ot 5v so long as you can get a definate logic high and logic low

Shaun