I was just wondering if a given pin, configured as input, and used as either a UART Rx line, external INT line, etc... should have pullups enabled or not? Or does it matter? I hadn't thought this should be done until recently noticing that if my serial device was unplugged, or external lines not connected, I would have interrupts triggering erroneously... but enabling pullups seemed to fix this. So then I began to wonder if it was just considered standard practice to always enable them when using a pin as input for these types of reasons? I've read the datasheet many times looking for guidance and couldn't find it anywhere... so any comments would be greatly appreciated!