Tiny BLDC motor controllers can be had for under 1.5 cents, plus a microcontroller (which most devices have anyway). (six 1 amp mosfets, plus a few passives, an

Tiny BLDC motor controllers can be had for under 1.5 cents, plus a microcontroller (which most devices have anyway). (six 1 amp mosfets, plus a few passives, and about 1 cm^2 of board area)). Unfortunately they normally need a control loop that runs at at least 10kHz for saliency measurement, which means all the other code on the microcontroller needs to be well behaved and not have millisecond long critical sections. If you can't do that, you need to add another 5 cents for another microcontroller.