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resources:vga_drawer [2019/05/10 12:28] jgoeders [Drawing Pixels] |
resources:vga_drawer [2019/05/13 13:12] (current) jgoeders |
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| - | ====== The VgaDrawer Module ====== | + | ====== The BitmapToVga Module ====== |
| =====Resources ===== | =====Resources ===== | ||
| - | {{ :resources:vgadrawer.sv | VgaDrawer.sv}} | + | {{ :resources:BitmapToVga.sv | BitmapToVga.sv}} |
| {{ :resources:clk_generator.v | clk_generator.v}} | {{ :resources:clk_generator.v | clk_generator.v}} | ||
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| ===== VGA Video ===== | ===== VGA Video ===== | ||
| - | You have been given a module, ''VgaDrawer'', that generates the signals necessary to send 640x480 video out over the VGA port on the board. | + | You have been given a module, ''BitmapToVga'', that internally stores a Bitmap image, and continually sends the image out over the VGA port on the board as 640x480 video. |
| - | 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. | + | Internally, the bitmap image is 320x240 pixels. 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. Upon power-on, the bitmap image will be all black, but using the inputs to the ''BitmapToVga'' module, you can change the color values of the 320x240 pixels, one at a time. |
| - | The bitmap image is 320x240 pixels, and ''VgaDrawer'' automatically scales up the image to the 640x480 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 640x480 image). | + | Note: Although the VGA output is 640x480, the bitmap is only 320x240 pixels, because the limited memory on the FPGA would make it difficult to store a full 640x480 image. The ''BitmapToVga'' module automatically scales up the image to the 640x480 resolution before sending it to the display. |
| - | ^ Module Name = VgaDrawer ^^^^ | + | ^ Module Name = BitmapToVga^^^^ |
| ^ Port Name ^ Direction ^ Width ^ Description ^ | ^ Port Name ^ Direction ^ Width ^ Description ^ | ||
| | clk | Input | 1 | 100 MHz Clock | | | clk | Input | 1 | 100 MHz Clock | | ||
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| ==== Drawing Pixels ==== | ==== Drawing Pixels ==== | ||
| - | The ''VgaDrawer'' module has inputs that let you change the value of the pixels in the bitmap image, allowing you to draw things on the VGA monitor. | + | The ''BitmapToVga'' module has inputs that let you change the value of the pixels in the bitmap image, allowing you to draw things on the VGA monitor. |
| The (x,y) layout of the bitmap is shown below: | The (x,y) layout of the bitmap is shown below: | ||
| Line 42: | Line 42: | ||
| {{:labs:lab_pong:pixel_writing.png |}} | {{:labs:lab_pong:pixel_writing.png |}} | ||
| + | \\ | ||
| + | \\ | ||
| + | \\ | ||
| ==== VGA Clock ==== | ==== VGA Clock ==== | ||
| - | The ''VgaDrawer'' requires a 25MHz clock. This is because the 640x480 VGA standard requires that pixels be sent at a rate of ~25MHz. | + | The ''BitmapToVga'' requires a 25MHz clock. This is because the 640x480 VGA standard requires that pixels be sent at a rate of ~25MHz. |
| You have been given the ''clk_generator'' module that uses special circuity on the FPGA (a Phase-Locked Loop (PLL), https://en.wikipedia.org/wiki/Phase-locked_loop) to derive a new clock based on the input 100MHz clock. | You have been given the ''clk_generator'' module that uses special circuity on the FPGA (a Phase-Locked Loop (PLL), https://en.wikipedia.org/wiki/Phase-locked_loop) to derive a new clock based on the input 100MHz clock. | ||
