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Topic: pin 2 pullup res (Read 633 times) previous topic - next topic

Boffin1

On a freestanding board I saw it is recommended to put a 10 k pullup resistor from pin2 to Vcc to avoid noise.

Can I just set it to an input and take it high to enable the internal pullup?  

robtillaart

As allways it depends on the context, Why was it recommend on the freestanding board? What was the question/application there? What type of noise?

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

retrolefty

If the chip has a fairly recent arduino bootloader installed I believe it already sets the internal pull-up on to prevent the bootloader from responding to noise on pin 2 and hanging the chip up waiting for an upload that is not coming. If the chip does not use a bootloader then there is not concern about noise on pin 2.

Lefty


Boffin1

Thanks, it did seem odd when there are pull ups in the chip... I have seen it mentioned several times.

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