What precautions should be followed when attaching circuits to AVR inputs pins while the AVR is powered?
I will be connecting other digital devices to the AVR, and I'd like to make it safe for the user to connect and disconnect them without having to turn off power beforehand. The peripheral devices will be things like other microcontrollers, CMOS logic chips and just simple phototransistors, and they will get they power from the AVR board.
Is there any danger of CMOS latchup either on the AVR side or on the peripheral side? Is there any extra protection I can add to guard against ESD? Are they any special connectors which will help in this regard?