GPIO as Input locks-up

[jeff belz]

Wondering if anyone has ever experienced this. I have several inputs I'm looking at. I poll them every 10mS. 99% of the time everything works, but sometimes the an input on PORTE will not read the correct logic. It locks at logic 1. If I look at the other inputs, then are fine. These inputs are connected a a Schmitt trigger optical switch. Could the speed of the switch be too fast at times, that it locks up my pin. My pin speed in low. thinking about changing it to high? it's a very strange issue. Even after a reset, the pin logic is still locked. Only a power cycle has worked

[AScha.3]

pin speed is only for output stage speed.

to limit input speed just put 10 kOhm in input line, this will make input signal more slow.