Motor control circuit overcurrent protection

A motor control circuit comprising a microcontroller 4 operable to provide a driving current to the windings 1 of a motor having an interrupt input 13 which when triggered ceases the driving current to the windings. A threshold circuit is provided to determine a reference level 10 which is compared to a signal indicative of the motor winding current 9 by comparator 8. If the winding current 9 exceeds the threshold value 10 the interrupt input 13 is triggered. The threshold value may be variable being controlled by software which adjusts the frequency or mark space ratio waveform, of output 16, in conjunction with a low pass filter 14 and 15. Alternatively the threshold value 10 may be fixed and determined by resistors 11 and 12.