is permanently a high one while a maximum speed demand persists indefinitely this could obviously cause the user to suffer an accident and the microcontroller is therefore provided with an algorithm adapted to detect possible abnormal input levels in the case of continuous level inputs which is the case of the potentiometer the identification of an abnormally high level is based on the comparison of the input level with a pre set threshold such a threshold is calculated in such a manner as to take the normal maximum input level and the related tolerances into due account in the case of pwm type inputs the identification algorithm starts by detecting the disappearance of the ramps or edges of the input signal absence of pwm modulation starting from this moment the microcontroller therefore measures the voltage level of the pwm filtered signal a see fig5 and enables the protection mode state 6 when the filtered voltage drops below a given threshold even the protection against abnormal inputs requires just a few dozens of milliseconds to become effective should the reference speed input decrease below the minimum speed threshold the microcontroller switches back to the stand by state and as a result the switching off switch opens therefore when the voltage is applied but the speed.