VGA timing

By xantus on Thursday 4 March 2010 07:43 - Comments (1)
Category: Verilog examples, Views: 7.362

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)64048096486401525 MHz
VGA (85Hz)64048058796405836 MHz
SVGA (60Hz)800600128888004040 MHz
SVGA (75Hz)800600791588001549 MHz
SVGA (85Hz)800600621528003456 MHz
XGA (60Hz)102476813616210242665 MHz
XGA (70Hz)102476813514210242375 MHz
XGA (85Hz)10247689520910244795 MHz

Table 1 – VGA horizontal timing specification

VGA ModeVertical Timing Spec.
ConfigurationResolutiona (lines)b (lines)c (lines)d (lines)
VGA (60Hz)64048023348010
VGA (85Hz)6404803254801
SVGA (60Hz)8006004236001
SVGA (75Hz)8006003216001
SVGA (85Hz)8006003276001
XGA (60Hz)10247686297683
XGA (70Hz)10247686297683
XGA (85Hz)10247683367681

Table 2 – VGA vertical timing specification

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


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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