Abstract: A 2-phase BLDC motor is driven by a trapezoidal waveform. For one-half of the motor rotation period T, the phase is driven by the trapezoidal waveform and for the other half-period, the coil remains undriven. An up down counter is operable to increment at a first frequency f1 and to decrement at a second frequency f2. Incrementing operation is initiated at the start of the driven period of the waveform and stopped at the start of the down slope of the waveform. Decrementing operation is initiated at the start of the down slope of the waveform and stopped at the end of the down slope. The ratio of frequencies f1:f2 is used to measure the relative duration of the slope to the driven period and is selected to mirror the desired ratio of slope duration:driven period duration.

Abstract: A 2-phase BLDC motor is driven by a trapezoidal waveform. For one-half of the motor rotation period T, the phase is driven by the trapezoidal waveform and for the other half-period, the coil remains undriven. Accordingly, if the optimum slope duration is around 10% of the duration of the driven portion, then it is of the order of T/20. An up down counter is operable to increment at a first frequency f1 and to decrement at a second frequency f2. Incrementing operation is initiated at the start of the driven period of the waveform and stopped at the start of the down slope of the waveform. Decrementing operation is initiated at the start of the down slope of the waveform and stopped at the end of the down slope. The ratio of frequencies f1:f2 is used to measure the relative duration of the slope to the driven period and is selected to mirror the desired ratio of slope duration:driven period duration.