how do i figure out hall sensor spacing?

polessymfield strength

“sensored” brushless motors typically use three bipolar latching hall sensors (like these Allegro A1250s) spaced 120 electrical degrees to make the classic 6 step block commutation waveforms that look like this:


the “bipolar latching”-ness makes them less susceptible to noise. The field reading must cross zero, plus a bit of threshold before the sensor changes state.