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The VgaDrawer Module
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You have been given a module, VgaDrawer, that generates the signals necessary to send 640×480 video out over the VGA port on the board.
Internally, the module contains a small memory that stores a bitmap image. This image is continually sent out over the VGA port. For each pixel in the image, 3 bits are stored: 1 bit for red, 1 bit for green, and 1 bit for blue. For example, a pixel set to 3'b000 will display black, 3'b111 white, 3'b100 red, 3'b010 green, 3'b001 blue, 3'b101 magenta, 3'b011 cyan and 3'b110 for yellow.
The bitmap image is 320×240 pixels, and VgaDrawer automatically scales up the image to the 640×480 resolution that is sent to the monitor. (This is done because the limited memory on the FPGA would make it difficult to store a full 640×480 image).
| Module Name = VgaDrawer | |||
|---|---|---|---|
| Port Name | Direction | Width | Description |
| clk | Input | 1 | 100 MHz Clock |
| clk_vga | Input | 1 | 25 MHz Clock for 640×480 VGA Display |
| reset | Input | 1 | Active-high reset |
| x | Input | 9 | x-Coordinate of pixel to modify (0..319) |
| y | Input | 8 | y-Coordinate of pixel to modify (0..239) |
| color | Input | 3 | Color of pixel. [2]=red, [1]=green, [0]=blue |
| wr_en | Input | 1 | Write enable. Set to 1 to enable writing to the bitmap image. |
| VGA_R | Output | 4 | VGA Red (to external connection) |
| VGA_G | Output | 4 | VGA Green (to external connection) |
| VGA_B | Output | 4 | VGA Blue (to external connection) |
| VGA_hsync | Output | 1 | VGA Horizontal Sync (to external connection) |
| VGA_vsync | Output | 1 | VGA Vertical Sync (to external connection) |
