7.3.5 Video Control Signals
The video control signal bits embedded in the high-speed FPD-Link LVDS are subject to certain limitations relative to the video pixel clock period (PCLK). By default, the DS90UB947-Q1 applies a minimum pulse width filter on these signals to help eliminate spurious transitions.
Normal Mode Control Signals (VS, HS, DE) have the following restrictions:
- Horizontal Sync (HS): The video control signal pulse width must be 3 PCLKs or longer when the Control Signal Filter (register bit 0x03[4]) is enabled (default). Disabling the Control Signal Filter removes this restriction (minimum is 1 PCLK). See Table 10. HS can have at most two transitions per 130 PCLKs.
- Vertical Sync (VS): The video control signal pulse is limited to 1 transition per 130 PCLKs. Thus, the minimum pulse width is 130 PCLKs.
- Data Enable Input (DE): The video control signal pulse width must be 3 PCLKs or longer when the Control Signal Filter (register bit 0x03[4]) is enabled (default). Disabling the Control Signal Filter removes this restriction (minimum is 1 PCLK). See Table 10. DE can have at most two transitions per 130 PCLKs.