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Arduino

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  • That seems odd, and not expected. The inputs on a CMOS device like an Arduino should be capacitive, and draw almost no current once they settle on their state. (It takes a small amount of current to drive the capacitor on the input to the high state, but then once it's charged, current flow should drop to the leakage current of the capacitor.) Commented Dec 10, 2019 at 18:22
  • Could you put the pin through a 10K resistor to ground when your switch is closed? That should be enough to pull the pin low, but greatly reduce the current flow. Commented Dec 10, 2019 at 18:22
  • You write that the "attiny85 draws around 3mA", so did you measure the current that is sunk by the pin or is it the current consumption of the entire chip? Does it change when you don't configure anything? Also, measuring current to detect the state of a switch seems way too complicate, you could probably read the voltage level at the switch directly. Commented Dec 10, 2019 at 18:57
  • 3 mA is a normal current draw for an ATtiny85 @ 3 V and 8 MHz. This has nothing to do with the input pin, it's just the current the AVR core needs to execute whatever instructions you ask it to execute. Commented Dec 10, 2019 at 19:29
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    On your devboard PB3 is connected to +5V over two resistors (1.5 k + 66.5) Ohms. That's the reason for the high current. Not the PU Resistor. ;-) See the scematics s3.amazonaws.com/digistump-resources/files/… (5/1560 = 0.0032051) Commented Dec 11, 2019 at 16:30