I was looking for a unipolar hall sensor that detects and counts the moments that the magnet passes it. This way I only have to detect once per rotation. Why can I read 6 digital pins? The uno has 13 digital pins or do I miss something?
Will the 1284P work together with an Uno or Nano?
Anyway, it has to (edit) detect the revelations and once every 100ms or so, calculate the RPM. Basically, it needs to detect how long ago the last detection was, this way I can calculate the RPM. So it only has to "remember" the last detection as wel as the shortest (highest RPM). Then, every 100ms or so, write the RPM to SDCard. Or into a variable and then once a 1 second, clear that VAR to SD.
I read somewhere that the DUE would be End Of Life but now I see that I can still order it.