VGA timing

By xantus on Thursday 4 March 2010 07:43 - Comments (1)
Category: Verilog examples, Views: 7.694

Figure 1 illustrates the basic timing requirements for each row (horizontal) that is displayed on a VGA monitor. An active-low pulse of specific duration (time a in the figure) is applied to the horizontal synchronization (hsync) input of the monitor, which signifies the end of one row of data and the start of the next. The data (RGB) input on the monitor must be driven low for a time period called the back porch (b) after the hsync pulse occurs, which is followed by the display interval (c).During the data display interval the RGB data drives each pixel in turn across the row being displayed. Finally, there is a time period called the front porch (d) where the data (RGB) inputs must again be off before the next hsync pulse can occur. The timing of the vertical synchronization (vsync) is the same as shown in Figure 3.9, except that a vsync pulse signifies the end of one frame and the start of the next, and the display area refers to the set of rows in the frame. Tables 1 and 2 show, for different resolutions, the durations of time periods a, b, c and d for both horizontal and vertical timing.

VGA timing
Figure 1 – VGA timing specification

VGA ModeHorizontal Timing Spec.
ConfigurationResolutiona (pixels)b (pixels)c (pixels)d (pixels)Pixel clock
VGA (60Hz)640×48096486401525 MHz
VGA (85Hz)640×48058796405836 MHz
SVGA (60Hz)800×600128888004040 MHz
SVGA (75Hz)800×600791588001549 MHz
SVGA (85Hz)800×600621528003456 MHz
XGA (60Hz)1024×76813616210242665 MHz
XGA (70Hz)1024×76813514210242375 MHz
XGA (85Hz)1024×7689520910244795 MHz

Table 1 – VGA horizontal timing specification

VGA ModeVertical Timing Spec.
ConfigurationResolutiona (lines)b (lines)c (lines)d (lines)
VGA (60Hz)640×48023348010
VGA (85Hz)640×4803254801
SVGA (60Hz)800×6004236001
SVGA (75Hz)800×6003216001
SVGA (85Hz)800×6003276001
XGA (60Hz)1024×7686297683
XGA (70Hz)1024×7686297683
XGA (85Hz)1024×7683367681

Table 2 – VGA vertical timing specification
http://www.greenbird.info/img.php?h&b=vga-timing&f

Volgende: 7 Segment Displays 03-'10 7 Segment Displays
Volgende: Rotary Encoder 03-'10 Rotary Encoder

Comments


By Cuica, Tuesday 20 August 2013 00:40

But although it cocnnets to projector, you can only use it to show videos; if it connected the whole desktop of the iPad & everything on it (powerpoint etc) then I could throw away my laptop. C'mon iPad!!

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