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[on:]

I've just built an arduino clone using a atmega328 chip.
It seems to work just fine without a resistor on pin 1.

I was under the impression it would continually reset without it?

or have I just gotten the wrong end of the stick....?

[Reply #1 on:]

I believe there is a weak internal pull-up on pin 1.

[Reply #2 on:]

Previous discussions have gone ovef erratic behavior without the external pullup.
Atmel Application notes seem to suggest having one, especially with DTR cap, external reset switch connected.

[Reply #3 on:]

I have personally had zero problems with it while tinkering around, but I have never left it out on something that's going further than a evening on the breadboard, as I have been able to reset the chip by waving my finger over it once before

[Reply #4 on:]

Yes it will work without it but not reliably. That means under all conditions of noise and temprature.

[Reply #5 on:]

The internal pull up is very weak. I built an attiny13 project and without and external pullup resistor, it occasionally resets by itself.