# How to interrupt Arduino with voltage input?

**URL:** <https://forum.arduino.cc/t/how-to-interrupt-arduino-with-voltage-input/1114961>\
**Category:** Programming\
**Created:** [April 14, 2023, 4:24am UTC](https://forum.arduino.cc/t/how-to-interrupt-arduino-with-voltage-input/1114961 "2023-04-14T04:24:21Z")\
**Posts on this page:** 1\
**Showing post:** 18

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**Author:** ![PerryBebbington](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/perrybebbington/32/238766_2.png) [@PerryBebbington](https://forum.arduino.cc/u/PerryBebbington)\
**Post date:** [April 14, 2023, 6:44am UTC](https://forum.arduino.cc/t/how-to-interrupt-arduino-with-voltage-input/1114961/18 "2023-04-14T06:44:06Z")

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> [@Common ground and why you need one](https://forum.arduino.cc/t/common-ground-and-why-you-need-one/626215):
>
> A common mistake for people new to electronics is to have 2 circuits fed from different power supplies with signals passing between the circuits, but with the grounds not connected. This leads to questions asking why the project doesn't work. You don't have to spend long reading the questions on this forum to see this is asked often. Here I attempt to explain the problem and why it matters to connect the grounds. Note that in all of the schematics that follow I have used a battery as a power sup…

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