mirror of
https://github.com/cccb/servicepoint.git
synced 2025-01-18 10:00:14 +01:00
42 lines
1.5 KiB
Markdown
42 lines
1.5 KiB
Markdown
# About the display
|
|
|
|
- Resolution: 352x160=56,320 pixels
|
|
- Pixels are grouped into 44x20=880 tiles (8x8=64 pixels each)
|
|
- Smallest addressable unit: row of pixels inside of a tile (8 pixels = 1 byte)
|
|
- The brightness can only be set per tile
|
|
- Screen content can be changed using a simple UDP protocol
|
|
- Between each row of tiles, there is a gap of around 4 pixels size. This gap changes the aspect ratio of the display.
|
|
|
|
### Binary format
|
|
|
|
A UDP package sent to the display has a header size of 10 bytes.
|
|
Each header value has a size of two bytes (unsigned 16 bit integer).
|
|
Depending on the command, there can be a payload following the header.
|
|
|
|
To change screen contents, these commands are the most relevant:
|
|
|
|
1. Clear screen
|
|
- command: `0x0002`
|
|
- (rest does not matter)
|
|
2. Send CP437 data: render specified text into rectangular region
|
|
- command: `0x0003`
|
|
- top left tile x
|
|
- top left tile y
|
|
- width in tiles
|
|
- height in tiles
|
|
- payload: (width in tiles * height in tiles) bytes
|
|
- 1 byte = 1 character
|
|
- each character is rendered into one tile (mono-spaced)
|
|
- characters are encoded using code page 437
|
|
3. Send bitmap window: set pixel states for a rectangular region
|
|
- command: `0x0013`
|
|
- top left tile x
|
|
- top left _pixel_ y
|
|
- width in tiles
|
|
- height in _pixels_
|
|
- payload: (width in tiles * height in pixels) bytes
|
|
- network byte order
|
|
- 1 bit = 1 pixel
|
|
|
|
There are other commands implemented as well, e.g. for changing the brightness.
|