What does "5V tolerant I/O" mean?

Hardware Arduino 101
1

The Tech Spec tab here says that the 101 has "5V tolerant I/O".

Now, I know what it means for an input on a 3V system to be 5V tolerant, but I don't know what it means for an output to be 5V tolerant. (Or for that matter, to be tolerant at all.)

Does "5V tolerant I/O" mean that a 101 output pin supplies 5V, or does it really just mean the inputs are tolerant of 5V and the "I/O" part is just a misnomer? Or something else?

2

Quoting from the page you reference "The board operating voltage and I/O is 3.3V but all pins are protected against 5V overvoltage. " pretty much tells the story. Your output will be approximately 3.3V, and your digital inputs will read anything between 3.3V and 5V as if the input was 3.3V. if you actually need 5V output, you will need a transistor circuit to boost the output voltage, or something like the SparkFun Logic Level Shifter (https://www.sparkfun.com/products/12009).

3

Hi optoaudio,

or does it really just mean the inputs are tolerant of 5V and the "I/O" part is just a misnomer?

Yes this is the answer.

Marco

4

Sorry I was wrong :-[ :-[ :-[

An output can be in tri state, and then a voltage can be applied to it.

So an output "5 V tolerant" means that can tolerate 5V on it, when it is in tri state.

Marco