I've just ordered a couple of XBee Adaptor kits to interface to an ATMega1280. The schematic shows the DOUT pin connected directly to the header pin. (I appreciate also that all the buffers in the 74AHC125N have been used.)
Given that mistakes do happen and the corresponding Rx pin on the AVR could be accidentally set to an output (and high), would the XBee tolerate 5v applied to DOUT? Or would it be prudent for me to buffer DOUT up to 5v and at the same time, offer some protection to the XBee?
I realise that I'm being overly cautious ... but that's me :D