I have what will likely turn out to be a foolish question, but I'm going to ask it anyway... :oops:
I'm considering re-designing one of my projects to use an AVR Mega controller (a Mega1280 or 2560, not sure which yet...) as a replacement for the 8052-based controller it currently uses - in order to integrate the 12-channel ADC into the controller and save a bit of board-space and cost.
My dilemma is that several of the pins will be driving relays for which it is *absolutely essential* that they not close before they are commanded... so I need to avoid transients at all costs.
I'm still poring over the datasheets, but am unable to find out what the pin-states are following a reset. If I'm reading them correctly, the pins default to a tri-state configuration, instead of the pulled-high state that the 8052 variants start in. While I doubt that a transistor would activate in such a state, the paranoid part of me is concerned.
Now, given the number of IO pins that are potentially available on these 100-pin devices, I can use optocouplers with the A and K leads each sent to a different pin... but I'd like to use transistors to drive the relays if at all possible.
Is it safe for me to assume that the pins start in an active-low state, and that any transistors I install will remain off until I program them to turn on?