Thank you for your answers !
My mechanical setup can’t roll backwards, think of it as a disk spinning such as in an old generation electrical meter. I would like to never miss a revolution. I would be putting a magnet on the disk, detected by the reed switch/hall sensor at every spin.
I know the normal Arduino boards need modification to run at ultra low sleep power, my question was more about how to make them run as such sleep power while the counter based on the reed switch/hall sensor can still count at a very low power too.
I would expect a pulse from the sensor around once every minute - once every 2 minutes
In this case we can imagine a timer sleep wakeup every 2 seconds or something, but again, I really don’t want to miss a revolution, and I want to be protected that if randomly the installation is at sleep when the magnet comes in contact with the reed switch it is aware of it and counts it.