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The Dot Factory is a small, GPL, open source tool intended to generate the required C language information to store many fonts and images, as efficiently as possible, on a microcontroller. These fonts are then uploaded via the LCD driver (see the Drivers and Modules page for a few) to the actual dot matrix LCD. It is written in C# for Visual Studio 2008 and has been tested on Windows XP, 2003  and Vista.

Working with dot matrix LCDs with microcontrollers, while not difficult, is tedious. The actual LCD controller allows us to upload simple visual data (dot on or dot off) into the LCD's dot matrix, but not much else. It is up to our software to decide what to upload when we want to draw lines, circles and more importantly - text. While there are software graphic libraries that allow us to generate a character "on the fly" using vector graphics (the character is described as a series of drawing commands that allow scaling and decoration) - these are much too complex and large to integrate in a microcontroller environment. Consequently, we must store the exact appearance of a character as a series of 1s and 0s, equivalent to a "dot on" "dot off" on the LCD, and upload this as a bitmap when we want to display text. While it is possible to generate this manually, it is desired to have a tool to do our grunt work by converting windows fonts (given a size and decoration) into a series of bitmaps.

Using The Dot Factory

TDF is comprised of two panes - the input pane on the left (what you want to generate) and the output pane  on the right (the generated output, in C code). The input pane can accept either a font of your choice (for writing text to the LCD) or an image. When generating a font, you have the option of either generating all the available letters (by selecting "All" in the Insert Text box and clicking the plus button) or by typing in which letters, numbers or symbols you are actually using in your application (for example: 0123abcd). If you are writing a simple application that has only a few sentences, you can type them wholly in this box without fear of duplicating letters - TDF takes care of that by discarding any duplicates. This way only the letters you use will take up space.

Once you have completed setting up what it is you'd like to generate (be it an image or font), select the output method in the output pane. If you are using the LCD drivers on this website, you want it to generate an MSb first output, otherwise images will come out wrong. If you have a compiler that supports the "0b" binary specifier, you can select "binary" rather than "hex". This will allow you to visually see the pixels you will set and allow for manual touch up by the user without having to calculate hex and experimentation. Click generate and your C code will be outputted to the text box below. Copy paste this into your application (it is recommended to put this in a separate module, not your LCD driver module, for organizational reasons).

What does it generate?

• The character bitmap array: This holds the actual characters as a bitmap (only the characters selected in the input pane). Each byte represents a single vertical page sent to the LCD. All vertical padding is removed from the characters
• The character descriptor array: Allows O(1) mapping between a character's ASCII value and required meta information about the character - namely its width in bits and its offset into the character bitmap array. When the LCD driver needs to find where character X is located in the bitmap array, it will jump to index [X - font.startCharacter] in the descriptor array. The startCharacter is the first character (that is, the character with the lowest ASCII value) used for this font. By defining a startCharacter we can reduce the number of elements in the descriptor array.
• The font information: This element is essentially the font descriptor for this font. It holds information regarding this font like the name of the character bitmap and descriptor arrays, the font start character and how many pixels wide a space character is for this font. The LCD driver will replace the space character with empty pixels (this saves both processing time, space in the character bitmap array and space in the character descriptor array - since the space is the first ASCII character and is commonly used).

The generated structures are generated with documentation, but you may want to see the bitmapDb header file in the drivers page for detailed info on the character descriptor array and font information structures.

For image generation, only the image's bitmap array and size descriptors are generated. Note that the height value is pixels (bits) and width values are in pages.

Revision History

• Version 0.0.6 (03mar10): Bug fix for image generation (tried to save a temporary file for debugging in a custom directory) - thanks to Nir Shemesh for pointhing this out!
• Version 0.0.5 (23dec09): Added support for rotation (90 degree increments), space character generation, width (bit/byte) selection of character width and font height, optional generation of character height/width and font height, structures are now generated with documention, input text and font is persisted throughout invokations of the application, persistent preset management - add, edit, delete output configuration presets
• Version 0.0.4 (31jul09): Added a space to end of comments in the char descriptor array to prevent preprocessor misinterpreting '\' as a newline
• Version 0.0.3 (30jul09): Added output configuration: hex/binary, MSb First/LSb first, configurable padding removal, comment control, flip X/Y and more
• Version 0.0.2 (28jul09): Vista support
• Version 0.0.1 (25jul09): Initial release (flip not supported, output format not supported, not tested on Vista)

For the next version

I'm trying to get TDF to a point where it will be flexible enough to generate most of the formats people need (this will, of course, take time). Since I am not familiar with all possible formats, I will need your help. If you'd like to suggest an output format, drop me a line and I will try to make sense of it.

• Select between generating pages from rows or columns (to allow more efficient 0/180 degree encoding) - as suggested by Darcy
• Detect Unicode characters and modify output accordingly (i.e. do not generate a lookup array) - as pointed out by Christian Treczoks

Download

• Latest stable binary (0.0.6): Windows Vista/XP/2003, requires .NET framework 3.5
• Latest stable source (0.0.6): C#, Visual Studio 2008 project [express supported]
• Previous binary (0.0.4)
• Previous source (0.0.4)