[Al Skierkiewicz]

Omar,
The continuity test was between the 0v terminal on the VRM and 0v terminal on the Roborio (my interpretation). While continuity necessarily provides a voltage, it really didn't make a lot of sense as to why this actually worked. The OP also stated he was using the NPN output of the Banner sensor which is an active low when sensed. My suspicion to this point is again the very low current provided by the 40k pullup. I would not, however, recommend a pull up to 5 volts in parallel with the internal pullup to 3.3 volts. That would tie both supplies together and would draw current dependent on the state of the input as connected. I was suggesting that a 10k resistor be used as an additional pullup to the 3.3 volt buss. The 10k (in parallel with 40k) to 3.3v would produce near the current of a single 10k in a 5 volt pullup. Certainly something between 1k and 10k should work.