I'm implementing a system in a Cyclone III Dev Board and Bitec DVI daughterboard with different output resolutions using the CVO modes (Clocked Video Output from the Video Image Processing Suite) but whenever I change the input resolution the CVO stops working and I get no video output, my display enters sleep mode. Sometimes the CVO status bit reads 0, not all the time.
I tried writing 1 to the GO bit but it has no effect. I'm trying different pixel clock and cpu clocks for resolutions 1280x1024 and 1024x768: 110MHz pixel clock and 125MHz cpu clock 65MHz pixel clock and 100MHz cpu clock 110MHz pixel clock and 100MHz cpu clock I'm assuming the clock is modified inside the CVO or in the Bitec. Is that OK or do I need to change the clock frequency in run-time too? If so, is this done with the SOF functionality?