What do I do with the leftover Reset pin?

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1

Hi guys!

So I have been tinkering a lot with ATTINY circuits and building PCBs around them. All works like a charm so far, but I got me thinking about the Reset pin.

What is the proper way to "treat" it? I mean so far I have always just left it open-ended not connected to anything at all. Mostly because I do not need a reset button on any of my projects.

Can I just continue to leave it N/C? Or is there a "proper" way I should still connect it even if I do not intend to use it?

Thanks so much in advance!

2

The internal resistance is very weak. If you leave RESET enabled you have to add something external (e.g. 10 k ohm resistor) to hold it high. I know for a fact static electricity can cause spurious resets from an unconnected RESET pin.

(I tie RESET to VCC in my final versions.)

3

Does the ATTINY have a high voltage programming mode? The reset on the AVR's I have been using (328p, 1284p) lack a high side ESD diode so they can go over 12V and activate that programming mode.

4

ron_sutherland:
Does the ATTINY have a high voltage programming mode?

The ones I use do (tX5, tX4).

5

There's an internal pull-up on the RESET pin (30k--60k according to the specs) so leaving it with no connexion is fine.

6

Pull it up with a 10k resistor.

7

Especially in a "noisy" enviroment. Recommended in the App notes.