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42 lines
1.5 KiB
Markdown
42 lines
1.5 KiB
Markdown
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# About the display
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- Resolution: 352x160=56,320 pixels
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- Pixels are grouped into 44x20=880 tiles (8x8=64 pixels each)
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- Smallest addressable unit: row of pixels inside of a tile (8 pixels = 1 byte)
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- The brightness can only be set per tile
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- Screen content can be changed using a simple UDP protocol
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- Between each row of tiles, there is a gap of around 4 pixels size. This gap changes the aspect ratio of the display.
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### Binary format
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A UDP package sent to the display has a header size of 10 bytes.
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Each header value has a size of two bytes (unsigned 16 bit integer).
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Depending on the command, there can be a payload following the header.
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To change screen contents, these commands are the most relevant:
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1. Clear screen
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- command: `0x0002`
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- (rest does not matter)
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2. Send CP437 data: render specified text into rectangular region
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- command: `0x0003`
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- top left tile x
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- top left tile y
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- width in tiles
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- height in tiles
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- payload: (width in tiles * height in tiles) bytes
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- 1 byte = 1 character
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- each character is rendered into one tile (mono-spaced)
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- characters are encoded using code page 437
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3. Send bitmap window: set pixel states for a rectangular region
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- command: `0x0013`
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- top left tile x
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- top left _pixel_ y
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- width in tiles
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- height in _pixels_
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- payload: (width in tiles * height in pixels) bytes
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- network byte order
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- 1 bit = 1 pixel
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There are other commands implemented as well, e.g. for changing the brightness.
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