Lee Wrote:
"an A/D converter outputs an 8-bit binary value to a microcontroller port that is outputting all 0's."

Andy Wrote:
Why on earth would you do that????!!!!! :-0

That little OH-MY-GOD face is funny. Anyhow, I can think of two probable situations where this could happen:

1) I make a mistake when programming - maybe I accidently assert a RD signal at the wrong time or write data to the wrong port. I am not immune to brief lapses of coherence.

2) The program crashes (hardware or software reason) and executes code that it shouldn't execute.

Both situations seem like possibilities for the average system, and it never dawned on me that this could make it go up in smoke. That doesn't seem like good design practice to me (of course it may just be a fact of life?). And I don't see people inserting current limiting resistors between bidirectional devices "just in case".

Of course I have to read the datasheets - I did and it is obvious that it would drive both sets of port pins outside their recommended limits. But should I protect against this possibility or should I be extremely careful when coding and pray that the micro doesn't go haywire?

- Lee