XESS XStend XS40, Manual

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003- net s<2> loc=p19;
004- net s<3> loc=p17;
005- net s<4> loc=p18;
006- net s<5> loc=p14;
007- net s<6> loc=p15;
008- net rst loc=p45; // microcontroller reset
009- net oeb loc=p62; // RAM output enable
010- net dipsw<1> loc=p6; // DIP switch inputs
011- net dipsw<2> loc=p7;
012- net dipsw<3> loc=p11;
013- net dipsw<4> loc=p5;
014- net dipsw<5> loc=p72;
015- net dipsw<6> loc=p71;
016- net dipsw<7> loc=p66;
017- net dipsw<8> loc=p70;
018- net spareb
loc=p67; // SPARE pushbutton input
019- net resetb loc=p10; // RESET pushbutton input
020- net lsb<0> loc=p1; // XStend left LED digit segments
021- net lsb<1> loc=p2;
022- net lsb<2> loc=p3;
023- net lsb<3> loc=p75;
024- net lsb<4> loc=p79;
025- net lsb<5> loc=p82;
026- net lsb<6> loc=p83;
027- net lsb<7> loc=p84;
028- net rsb<0> loc=p58; // XStend right LED digit segments
029- net rsb<1> loc=p56;
030- net rsb<2> loc=p54;
031- net rsb<3> loc=p55;
032- net rsb<4> loc=p53;
033- net rsb<5> loc=p57;
034- net rsb<6> loc=p61;
035- net rsb<7> loc=p34;
036- net db<1> loc=p44; // XStend bargraph LED segments
037- net db<2> loc=p43;
038- net db<3> loc=p41;
039- net db<4> loc=p40;
040- net db<5> loc=p39;
041- net db<6> loc=p37;
042- net db<7> loc=p36;
043- net db<8> loc=p35;
Displaying Graphics from RAM Through the VGA Interface
This section discusses the timing for the signals that drive a VGA monitor and describes a
VHDL module that will let you drive a monitor with a picture stored in RAM.
VGA Color Signals
There are three signals -- red, green, and blue -- that send color information to a VGA
monitor. These three signals each drive an electron gun that emits electrons which paint
one primary color at a point on the monitor screen. Analog levels between 0 (completely
dark) and 0.7 V (maximum brightness) on these control lines tell the monitor what