This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute (RPM). You don’t need much… ...

This is an Arduino library that enables you attach an interrupt to any pin of Arduino Uno, Nano, Mini and other 328-based boards. The Arduino attachInterrupt () function only allows pines 2 & ~3.

Hit the same issue, as above moving pinmode after attachinterrupt fixes this pullup issue, but means the activation of the pull-up (or down) can cause an interrupt.