Pixel Clock Calculation

The following formula calculates the pixel clock frequency that you need to drive the pixel clock input port, clk_pixel.

PIX_CLK_MHZ >= (DATARATE_MBPS * NUM_DATA_LANE) / PACK_BIT,

where:
  • PIX_CLK_MHZ is the pixel clock in MHz
  • DATARATE_MBPS is the MIPI data rate in Mbps
  • NUM_DATA_LANE is the number of data lanes
  • PACK_BIT is the pixel data bits per pixel clock from Video Mode Pixel Encoding.

There is a FIFO for data transfer from the byte clock domain to the pixel clock domain. The pixel clock frequency is applied approximately equal to the formula given above (or, within ±100% to 150% of the calculated value). If the pixel clock frequency is too low, a FIFO overflow occurs (overflow happens when the read clock is slower than the write clock). If the pixel clock frequency is too high, a FIFO underflow occurs (which causes the pixel_data_valid to be in a toggling fashion within a one-pixel line).