An endoscopic system for use a controlled light environment is disclosed. In an implementation, the system may include an endoscope having an image sensor, an emitter, and a control circuit. The control circuit controls a frequency of the emitter in response to signals that correspond to the frequency of the emitter. The image sensor has input and output pads, where a pad count is reduced by not having a dedicated input synchronization clock pad. A frame period is divided into three defined states: a rolling-readout state during which image data is output through the pads, a service-line state during which non-image data is output through the pads, and a configuration state during which instruction data is received by the image sensor through the pads. Signal transitions are encoded within output data from the image sensor and correspond with defined states.
