VGA显示文字

1. VGA字符显示的原理

把要显示的字符转换成字符点阵，然后编码存储，着色的部分为1，其它为0.然后在VGA上输出显示。

字符点阵生成软件：

https://www.zhetao.com/fontarray.html

这里一个字符为32*32bit，字符点阵如下图：

字符编码存到内存里的代码如下：

 //char dot reg

 reg [159:0] char [31:0]; //5 char 32*32*5

 //字符“电子实验室”

always@(posedge clk)

    begin

        char[0]     <=  160'h0000000000000000000000000000000000000000;

        char[1]     <=  160'h0000000000000000000000000000000000000000;

        char[2]     <=  160'h00038000000000000007800000001e0000078000;

        char[3]     <=  160'h0003c000000001e00003c00000781f000007c000;

        char[4]     <=  160'h0003800007fffff00003e0007ff81e000003c000;

        char[5]     <=  160'h00038000078003f00001e00038783e000e01c030;

        char[6]     <=  160'h00038000000007e00e01e0000c703f000e01c038;

        char[7]     <=  160'h0e0381e000000f800e01c03c0f707b800ffffffc;

        char[8]     <=  160'h0fffffe000003e000ffffffc0f7073801e00007c;

        char[9]     <=  160'h0f0381e0000378000e00e03e1e70f3c01e0003f0;

        char[10]     <=  160'h0f0381c00003f0001e70f8781ef1e1e03e0007e0;

        char[11]     <=  160'h0f0381c00003e0003e7cf0f01cf1c0f03fffffe0;

        char[12]     <=  160'h0f0381c00003e0003c3ef0e01ce380fc038f8000;

        char[13]     <=  160'h0f0381c00003c038181ef0001ce701fe001f1c00;

        char[14]     <=  160'h0fffffc00003c07c000ef0001ceffffc003c0f00;

        char[15]     <=  160'h0f0381c07ffffffe0780f0001cfdc01800780780;

        char[16]     <=  160'h0f0381c07803c00003e0e0003ffc007001f003c0;

        char[17]     <=  160'h0f0381c00003c00001f0e0003c3f307803ffffe0;

        char[18]     <=  160'h0f0381c00003c00000f0e038003bb87803fffde0;

        char[19]     <=  160'h0f0381c00003c0000071e07c003bbcf001e381c0;

        char[20]     <=  160'h0f0381c00003c0007ffffffe00f9dcf00003e0c0;

        char[21]     <=  160'h0fffffc00003c0003801e0001ff9dee00003c180;

        char[22]     <=  160'h0f0381d80003c0000003c000ff39fee00003c3c0;

        char[23]     <=  160'h0f0381980003c0000003f8007839ffc007ffffe0;

        char[24]     <=  160'h0e0380180003c0000007fe002079efc00383c000;

        char[25]     <=  160'h000380180003c000000fbfc00079c1800003c000;

        char[26]     <=  160'h0003801c0003c000001f0fe01c7003980003c000;

        char[27]     <=  160'h0003801e007fc000007e03f01ff003bc0003c018;

        char[28]     <=  160'h0003fffe007fc00001f801f003fffffe0003c03c;

        char[29]     <=  160'h0003fffc000f80000fe000f001e700007ffffffe;

        char[30]     <=  160'h00000000000700007f0000700000000038000000;

        char[31]     <=  160'h0000000000000000000000000000000000000000;

end

1. VGA显示内容布局

规划要显示的内容：

这里还是以1个block（16*16bit）为色块基本单位，字符显示范围行15~25（不包含25）block内，列8~10（不包含10）block内。下面三个色块布局类似。

在字符显示范围内，有效位置1：

1. 总结

VGA字符显示，先规划字符大小，布局，利用字符点阵生成工具，然后限定显示范围，输出编码。其中，字符坐标要转换成像素坐标。字符正序显示，需要把坐标倒序处理。

参考：

https://mp.weixin.qq.com/s/WFioASjRQRj4KaSN1cCWkA