Abstract: A microcomputer with a built-in motor control circuit comprising a PWM generating circuit capable of automatically inverting a start level of PWM output or of changing the start level according to an optional preset pattern, an interruption request control circuit for controlling an interruption timing, and a multi-function reload register, is configured such that a start level content is inverted automatically at every period by setting a variable required for the conversion at a program executed on CPU when the start level content of the PWM output is inverted at every period, so as to make the setting unnecessary at every interruption.

Abstract: A PWM waveform generator has a cycle timer for generating pulses at regular intervals, and a duty timer for generating a pulse of a program-selected duration after each pulse from the cycle timer. A register stores one bit of data which designates whether the PWM output starts high or low at the beginning of each cycle. The pulses from the cycle timer are fed through gates controlled by the register contents to the set and reset terminals of a flip-flop. Pulses from the duty timer cause the flip-flop to toggle. The starting level can be changed in any PWM cycle by rewriting the data in the register.

Abstract: A microcomputer with a motor controller circuit includes a motor controller circuit (4) which has NAND circuits (8) for producing a logical product of a rise pulse from a rise pulse generator (5) and a start level from a register (7) and flip-flop circuits (9a-9b) each responsive to start level set signals from the NAND circuits and an output pulse from a three-phase inverter waveform generator timer (6a-6b) to generate three-phase inverter waveforms.