SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The timing generator state-machine reuses the synchronization information received through TAGs to:
For more details on the video port, refer to Section 9.2.2.2, CAL Integration - Video Port.
The timing generator can be unconditionally reset in the following ways:
It is also reset by data tagged as PIX_DAT_FS when the CAL_VPORT_CTRL2[16] FS_RESETS bit is set. This bit is enabled by default, but may be disabled when vertical blanking times are very short and there is no risk of TX data dropping/desynchronizing.
Four VP_PCLK cycles are sent before the first active pixel . The video port state-machine then waits until four VP_PCLK cycles are sent after the last blanking cycle of the frame .
Active data is sent to the video port only when at least 4 × CAL_VPORT_CTRL2[31:18] RDY_THR pixels are available. That mechanism can be used to smooth the pixel rate on the video port, if input data arrives at bursty rate. The video port FIFO accumulates 4 × CAL_VPORT_CTRL2[31:18] RDY_THR after frame start before it sends the first pixel, and signal VP_VS = VP_HS = 1.
The video port can generate horizontal and vertical blanking in addition to pixels received from the CAL pipeline. The amount of blanking is defined by the CAL_VPORT_CTRL1[24:17] XBLK and CAL_VPORT_CTRL1[30:25] YBLK bit fields. The pixel clock is active at the chosen speed during blanking. VP_HS pulses are provided during vertical blanking. The pixel clock is cut during the idle period.
The timing generator is stalled (VP_PCLK = 0, state-machine stalled) when the current position is in the active video region (waiting for data), but no data is available. VP_PCLK is free running (at the speed defined by CAL_VPORT_CTRL1[16:0] PCLK bit-field) during horizontal and vertical blanking periods. No line PIX_DAT_HS, PIX_DAT_HE, PIX_DAT_VS, PIX_DAT_VE tags are expected by the video port state-machine during blanking periods.
Software does not need to configure the size of the image for the video port. This information is extracted from the received datastream. Generally, to generate the vertical blanking, CAL counts the number of active pixels from the last image line.