it might be helpful if you could supply a little more information - as to what you're actually doing, where you need these parameters, and the specifications of the display you're using. Also, I'm not sure about some of your abbreviations. I gather that RR is Refresh Rate (sometimes called vertical frequency), HR is horizontal resolution, and VR is vertical resolution. I have no idea, however, what HGT1, HSP, SH1 and SH2 is.
Originally Posted by ramkumar218
Hallo Friends am very new to this topic,I have a doubt. In setting the parameters for Horizontal and Vertical timing for instance
Desired RR or Frame rate = 75 Mhz
Could u kindly let me know what will be appropriate value or how can HGT1 and HSP be calculated for getting SH1 and SH2 value and also VSP to find SV2..
First of all, the frame rate definitely isn't 75MHz, it's probably 75Hz. You're off by a factor of a million.
Multiply the frame rate (aka vertical frequency) by the number of scan lines (the vertical resolution), and you get the horizontal frequency. Note that many displays need a certain percentage of "invisible" scan lines for internal, technical reasons. So, with your figures I would take 600 scan lines (544 of which are visible), which yields a horizontal frequency of 600 * 75Hz = 45kHz.
Then multiply the horizontal frequency by the number of horizontal pixels (plus a few invisible ones), and you get the required pixel clock, that is, the speed at which your GPU has to generate its stream of pixels. Again, with your figures, I'm taking 1600 pixels across (1440 of which are visible), and I get a pixel clock of 1600 * 45kHz = 72MHz.
As I said, I have no idea what the other parameters are ...
By the way, I assume that your display is a flatscreen, not a CRT. Then there's no need to set a high refresh rate, since flatscreens are flicker-free by design. A refresh rate of 60Hz instead of 75Hz will do nicely. That would make the horizontal frequency drop to 36kHz, and the pixel clock to slightly below 60MHz, which is fine for many displays.
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