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Zedboard - VGA

metinburak_

The analog VGA connector is directly connected to the digital Zynq pins. Why isn't there any VGA DAC? How come is VGA interface implemented by digital pins?

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    Hi metinburak,

    The ZedBoard VGA connector is connected to the Zynq device via a R-2R resistor ladder configuration which gives 4-bits of resolution per color channel on the VGA interface.  Take a look at this Wikipedia entry to better understand this configuration:

    http://en.wikipedia.org/wiki/Resistor_ladder

    This is an implementation that the folks at Digilent have implemented on several development boards to avoid the cost of an additional VGA DAC chip.  There is an ISE based reference design project published on the Digilent ZedBoard product page which implements a test pattern generator out the VGA interface:

    http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,1028&Prod=ZEDBOARD

    Also, the folks at Xillybus have this VGA interface working with their Xillinux distribution so that may be another resource that is useful to you:

    http://xillybus.com/xillinux

    If you need better than VGA resolutions or wider than 4-bit per channel color space, I recommend looking at using the ADV7511 HDMI output on ZedBoard instead of VGA since there is more material available which covers the use of HDMI within a Vivado design.

    Regards,

    -Kevin

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  • 0

    Hi metinburak,

    The ZedBoard VGA connector is connected to the Zynq device via a R-2R resistor ladder configuration which gives 4-bits of resolution per color channel on the VGA interface.  Take a look at this Wikipedia entry to better understand this configuration:

    http://en.wikipedia.org/wiki/Resistor_ladder

    This is an implementation that the folks at Digilent have implemented on several development boards to avoid the cost of an additional VGA DAC chip.  There is an ISE based reference design project published on the Digilent ZedBoard product page which implements a test pattern generator out the VGA interface:

    http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,1028&Prod=ZEDBOARD

    Also, the folks at Xillybus have this VGA interface working with their Xillinux distribution so that may be another resource that is useful to you:

    http://xillybus.com/xillinux

    If you need better than VGA resolutions or wider than 4-bit per channel color space, I recommend looking at using the ADV7511 HDMI output on ZedBoard instead of VGA since there is more material available which covers the use of HDMI within a Vivado design.

    Regards,

    -Kevin

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