Imaging apparatus, including an imaging unit, which consists of an image sensor, configured to capture images of a region and to output image signals in response to the captured images and an illumination source, configured to illuminate the region. The unit further includes a driver circuit, which is coupled to receive a digital value indicative of a target luminous flux of the illumination source and to generate a pulse-width-modulated (PWM) signal to drive the illumination source with a duty cycle of the signal determined by the value. The apparatus includes a camera control unit, which is configured to process the image signals so as to generate images of the region and to output the digital value indicative of the target luminous flux based on the images. A single cable connects the imaging unit to the camera control unit so as to convey the image signals and the digital value.
