2 Arduino controller boards - 1 shared input

Question

I'm beginning with electronics and don't have all the good reflexes yet. So here is my question:

Can I do what I did here?

can i do this http://www.movod-design.com/forum_img/canIDoThis.jpg

Do I have to add diodes between the Nano +5V and the junction point?

My goal is to have one button's state read by 2 Arduino Nano.

Answer 1

You don't need to add anymore components to your schematic. But you can leave some components.

Before you're adding a button to your schematic please consider first how you want to detect your signal. A logic 1 as if a button is pressed? Or logic 0 as if a button is pressed. You can do this using pull-up and pull-down resistors. These resistors should be wired like this.

(The 100Ohm resistor in an internal resistor from the MCU)

Using the pull-down resistor means that when the button is pressed you'd get a logic 1. Using pull-up resistors means that when the button is pressed you'd get a logic 0.

When I see your schematic it seems like you're trying to make a pushbutton with pull-down resistor. Then you should wire your arduino like this.

Another option is to use the Arduino internal pull-up resistors. That way you don't have to add the 10k resistor in your schematic. And your schematic will look like this.

To use the internal pull-up resistors from the Arduino you'll need to put this in your setup(): pinMode(pin, INPUT_PULLUP); where pin should be your pin number. Please keep in mind that when you use the internal pull-up resistor a logic 0 means the button is pressed.

Answer 2

I have done something like this to be able to have a redundant system. Is this what you were doing: Two computers receiving the trigger, if one computer failed you have the other running?

If that is your case, then there is a problem on this setup:

• If one computer shuts down the Arduino on that computer will be powered by the second one and there will be not enough power for both.

I fixed it with a couple of diodes.

I still had some problems with false triggering from time to time, with tests on a Mac running OSX. The same tests with a Linux machine give no problem for now.

I wanted to make this really stable (next I'll try to use opto-isolators) I'm not a Programer nor a Engineer. Please tell me if I'm saying something stupid or if there is any other easy fix.

I was using two Arduino Pro micro Chinese copies and passing the data to midi to the computers - I did not test with real Arduinos to see if it was a board problem.