I wonder how to calculate pulldown resistor to make interrupt work? I need to connect 5 buttons to A0 and get pressing event via interrupts. Using different resistors, finally, I made work only 4 buttons. On 5th interrupt does not fire. Currently I use the following resistors for the buttons:
R1 Vout 0 5,00 2,7K 4,45 5K 3,70 10K 2,77 22K 1,78
And Pulldown Resistor = 22K.
If pulldown Resistor = 10K I can get event for 1-3 button only. Looks like the voltage 1,78V is quite low. But I’d liked make it work with 1V at most. I use RISING mode.
PS. Arduino Nano