Pressing/activating a push button logically?

Using Arduino Programming Questions
1

I have an external circuit board that is powered by 3v. It has a physical push button that I would like to push/activate logically. One side of this button has ground, when the button is pressed the other side is connected to ground and the circuit completes.

Now using an arduino, I know it might be easier to do this using a relay, transistor or optocoupler but I am trying to do this without any other components - is it possible?

I can connect one of the Arduino GPIO5 pin to the button and then do

pinMode(5, OUTPUT);
digitalWrite(5, LOW);

The above will work but the big question is when I do digitalWrite(5, HIGH) which essentially would be the rest state of the GPIO5 denoting that the button is not pressed, wouldn't this send a +3v causing a short circuit?

arduino-circuit

2

Only if you press that button at the same time and connect it also to ground.

A 1K or so resistor in the line between the GPIO and the other device could remedy that.

3

Would you care to share what model of Arduino? They are not all the same, you know?

5

Ah, makes sense!

6

I don't think it matters for the context of the question? (I don't have a specific board that I am using yet)

7

I know it does.

If you choose a 5V Arduino and connect it's GPIO pin to the input of a 3.3V device, the device could be damaged.

8

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