To perform automatic H/W (hardware) conversion without an MPU processing in the case of processing a change factor at the time of changing the value of a pulse string for comparison during an operation in the case of being composed of a reference pulse string and the pulse string for the comparison.

This circuit is provided with a means 101 for outputting the reference pulse string 111, an up/down counter 124, the means 123 for generating trigger signals to the up/down counter by the cycle of the natural number multiple of the cycle of PWM from input signals, the means 103 for comparing the output value of the up/down counter with the reference pulse string, the means 125 for holding output from the up/down counter, a setting means 121 for setting the value of the up/down counter by a software and the means 122 for mediating the operation by the trigger signals to the up/down counter and asynchronous setting to the up/down counter by the setting means 121.