Using RST pin as external power switch

Question

I have Arduino Nano with powered over USB. I have the request for external (physical) slide switch acting as power on/off for Arduino even if USB is always connected.

Looking at documentation and various posts, it seems the RST button could do just that. So when the "power" switch is on, RST is disconnected (= pulled high) and everything runs like normal. When the "power" switch is switched, it will pull RST low. As long as RST is pulled low, the board is stopped (the PWR led is lit, which is true and okay). Once released, the board will boot again.

Even though I agree this is not terribly elegant, is it going to work? I tried manually with the reset switch. Any side-effects I am overlooking?

Answer 1

That is a perfectly legitimate use of the RESET pin. Holding the chip in reset perfectly valid. Everything in the chip will be stopped.

Releasing it will start your sketch from the start again perfectly fine.

The only negative point is that your switch will be pulling power through the reset pin's pullup resistor, so will waste a little power.

• eudoxos: Thanks! The power is fine, I guess.