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Topic: ATMEGA328 DIP - All I/O pins have internall pull up/pull down resistors? (Read 302 times) previous topic - next topic

Ales

I have read
http://www.arduino.cc/en/Tutorial/DigitalPins
And i just want to bee 100% shure...
If i user
pins 6 + 11-14 for digital inputs
i can enable pull up/ pull down resistors for this pins, and i dont need external pull up/down resistors?


Thanx!


Paul__B

Forget "pull-downs" essentially no microprocessor ever has those; they are not useful for anything.

Yes, all digital I/O pins have an internal pull-up function if set as an input but written HIGH.

Ales

Yes, all digital I/O pins have an internal pull-up function if set as an input but written HIGH.

Thank you!

CrossRoads

Several ways to turn them on:
pinMode (pinX, INPUT_PULLUP);

or
pinMode (pinX, INPUT);
digitalWrite (pinX, HIGH); // turn on internal pullup

if set to an Input, then
digitalWrite (pinX, LOW); // turns off internal pullup

and as Paul indicated, there are no pulldown resistors.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

westfw

Quote
essentially no microprocessor ever has [pulldowns]
Actually, a lot of the ARM micros have configurable pulldowns, as do the Xmegas.

Paul__B


CrossRoads

"Stay on target (topic) Red Leader" - no pulldowns on uCs used in Arduino boards.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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