I have made a prototype for an rfid dooropener and I'm ready to do a proper build. Serial numbers of tags should go in eeprom and I have a way to add/remove the id's should there be new ones or if one gets lost. So it is a bit flexible and it will survive a power cycle.
I will have 5v, gnd and serial rx + tx going into a box outside that can be broken. If someone starts connecting these 4 -however unlikely that is- what can they break? I don't expect anyone to be able to enter as the Arduino is checking for a 12 character id being received over serial but I'd hate it if my little friend would be broken by a short-circuit.
Thanks for your ideas on this! Jhh