GPIO protection - resistor values

[JonnyAlpha]

Hi;

Can anyone confirm what size resistors I should be using to protect the GPIO or is it dependent upon the rest of the circuit?
Some examples are:

1. Values for pull up resistors when connected to 3.3v?
2. Resistors connected between LED and Gnd?

Thanks

[joan]

I have no electronics knowledge. From what I've seen on the forum.

1. The internal pull-ups/downs are circa 50k. I suggest something in the 5-20k range for external. I suppose it's best to use the highest value which works.

2. Depends on how bright you want your LEDs (modern ones seem too bright at maximum mA). I suggest something in the 330-1000 range. Suck it and see I'm afraid.

[rpdom]

People generally use 10K resistors for external pull-up/down as they are a very common value that most hobbyists have in their collection. It is worth getting a pack of those, and also 1K resistors, which can be used to protect the GPIO from overload if the GPIO is accidentally set as output while connected to ground or +V.

[mikronauts]

what they said

I normally use:

10k for pullups or pulldowns
470R for LED's