steffen
Posts: 2
Joined: Thu Mar 07, 2013 8:18 pm

Display pixel clock

Sun Mar 10, 2013 4:02 pm

Hello, I am new on Raspberry Pi and more hardware than software experienced. My Pi is runnung as expected, as long as I use a standard HDMI monitor. But I want to run a 640x160 display with it. This display has HDMI interface and provides proper edit data to the computer. It runs with graphics cards e.g. under Windows as long as they support such resolution.

The Pi could be forced to that resolution as well. Connecting the Pi with my Dell monitor it shows exactly this resolution as defined in the config.txt.

However the problem is, that the pixel clock is about 25MHz instead of the 10MHz needed for my display. It seems to me that tje lowest pixel clock is like in VGA resolution. I guess the chip must be able to support lower frequency as well, since the TV out also needs lower pixel clock.

Does anyone know how to adjust the settings to modify the pixel clock or maybe the non visible lines (H and V front- and backporch)?

Thanks for help, Steffen

Stevemo1
Posts: 2
Joined: Sat Feb 16, 2013 12:38 pm

Re: Display pixel clock

Sat Mar 23, 2013 4:06 pm

You say that this is working under Windows, what graphics card are you using to get a 10Mhz Pixel clock under Windows, please. Sorry, not much help to your original question, but I got here looking for an abswer to "what is the lowest pixel clock that the Pi will support", as I'm looking to run a low resolution as well

steffen
Posts: 2
Joined: Thu Mar 07, 2013 8:18 pm

Re: Display pixel clock

Sat Mar 23, 2013 4:18 pm

I was using a Nvidea Gforce graphics card to get low pixel clock. I also tried Intel but they didn't work.

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