5V Device, need to push and read a button.


So I am not getting very far here... Been at this a few days now.

I need to push a button on a device.

Someone suggested a DPST button vs. the SPST button that is already in my device, but DPST of the type and size I need are basically a myth.


I have a Computer Type device, that runs on 5V, that I can power the Arduino off of, and I need to interface with a N.O. button on the device. I was going to isolate the 2, but now I think I just want to read and write to that button.

I need to see if it is pressed, and have the Arduino automatically press it, every 86400000ms. (24 hours)

The Button is showing .42v for signaling.

Can i interface this button directly to pins on the arduino, take over for the button, and just run it through the arduino vs. directly to the device? (Use the arduino AS the botton?)

Please help.

Thank you !

Some questions...

  • Do you want to use the Arduino with the button, or do you want to replace the button with Arduino control?
  • The N.O. button on the device is showing 0.42V ... is the button pressed or open?
  • What is the button voltage in the opposite state?
  • Is this the voltage across the button contacts or from the button signal input to the device and GND?
  • How long will the wiring be from the Arduino to the button?


The button shows .42v when CLOSED. It seems to be a signaling voltage native to the circuit I am trying to interface with my Arduino.

So. Rather than try and recreate that signal, I shrink wrapped an LED to a Selenium Photo-resistor to use as a replacement for closing that switch.

I also managed to use the state change example to get most of the way to where I need to be on the code...


The state change example is way off from what I need and I am not sure how to change it to fit my need.

I have my device button (Original) properly pulled down with a resistor on PIN5

I have my Homemade Optocoupler on pin 12, with a 330ohm resistor for the LED inline to keep the volts low enough not to blow it. The selenium side is connected to my original switch input on the device mainboard. (The one I am trying to interface with)

Need the State of the button mirror the LED.
Need the LED not to latch and to only light while the button is pressed and immediately go off when it is not pressed.

I have a bank of 4 devices the button powers up and down.

The ideal setup for the button is as follows....

Pressing the Button 2 times, Flashes the Optocoupler LED 1 Time (for about 300ms)
(changing to the next of the 4 devices)

Pressing the Button 4 Times, Resets the 24 Hour timer.

Pressing the Button 6 Times, Lights the Optocoupler LED for 5 Seconds. (Saves the ON position of the original device)

Button counter resets after 10 seconds.

Pressing the Button to advance the device for the fourth time, sets all devices to OFF. So I need for the arduino to know how many times it has FLASHED the Optocoupler LED, so on the fourth time, it can press the button automatically on the original device 2x, so we reset to device position #1.

Does any of that make sense?

And Can you help me modify the state change code or point me in the right direction?

Please and Thank you!

P.S. I also want to show an LCD clock on the device at some point, reflecting the countdown of 24 hours. Is that possible on the Same Nano? Button switching, OptoCoupling, Auto Button Switching, and a Countdown Clock LCD?