Generation of the video timing output signals can be synchronized to the detected video timing input signals or generated independently by setting the SYNC_ENABLE field in the control register or selecting the GUI option to synchronize the generator to detector or fsync_in . Synchronization allows the generator to follow the phase of the detector timing. Synchronization of the output to the input allows the developer to override each individual timing signal with different settings such as signal polarity or start time. For example, the active video signal could be regenerated shifted one cycle earlier or later. This provides a flexible method for regenerating video timing output signals with different settings while remaining synchronized to the input timing.
The Video Timing Controller also has a GUI parameter, called Auto Generation Mode, to control the behavior of the generated outputs based on the detected inputs. When the Auto Generation Mode parameter is set, the generated video timing outputs will change based on the detected inputs. If this parameter is not set, then the video timing outputs will be generated based on only the first detected input format. (If the detector loses lock, the generated outputs will continue to be generated.) To change output timing while Auto Generation Mode is set, timing detection must first be disabled by clearing bit 1 in the Control Register and then re-enabling, if any of the Source Select bits are Low.