in a 9V circuit I want to check via digitalRead if a button is pressed.
However, putting 9V on a Arduino seems not to be a good idea for me, as it is working with 5V only.
Therefore I thought of adding another resistance to split the voltage, for example like that:
To receive 5V at the digitalRead, ideally I would need an 8kOhm resitor. However, I only have 10 kOhm and 1 kOhm resistors. So I am wondering, what are the detection limits for "HIGH" at an digital input. Will it work with 4.5V only?