I'm currently trying to read an AH276 hall effect sensor using an AVR microcontroller. The sensor is built-in in a brushless fan I'm using and it's operating as the fan's controller. The sensor has two output pins which drive the four coils of the fan (two pairs). My guess is that, using one of the two output pins (doesn't matter which one), I can count the RPMs of the fan. Is my guess correct?
If yes, how can I read the RPM without using an external sensor? Should I use a transistor on either AH276's output pin or I can connect it directly to an IO pin of the microcontroller? I have figured out the software part, but I'm stuck on hardware.
Both the microcontroller and the fan run at 5V.