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LED Matrix Projects.Thanks for clicking the led matrix extra projects link - I have not yet created all the projects and I need your help. Obviously it takes some effort to create the content in this site and I want to ensure that you are getting exactly the information you need. So could you complete the survey at the end of this page?Thanks very much. John... Sponsored Links...
The following is a brief discussion of the project book/course contents: ProjectsWith this project set you will learn how to drive the led matrix using interrupts and how to use buffers to scroll the display horizontally and vertically.Project examples :
All with full schematics
description and C source code.
Interrupt driven refreshTo drive the matrix properly you need to use a constant refresh rate that is independent of the executing code.While it is possible to drive the display without interrupts as for the original led dot matrix project it is far better to use interrupts. You can generate an interrupt at a pre-defined rate and refresh the display regularly without worrying too much what the code is doing in the mean time. The only thing to watch is how long the interrupt routine itself is (it must be shorter than the interrupt rate). BufferingBuffering is a useful concept used in all the high end graphics cards - you can think of the led matrix as 64 pixels in a screen display - and as such the techniques for updating it are the same as used in computer games.Each led represents one pixel - in this case one color - whereas in complex computer graphics a pixel is represented by one or more bytes but the principle of using them is the same. The scrolling display uses a buffer (an array) to store the led matrix data that is updated to the matrix at the screen refresh rate. Sponsored Links...
Note: The screen must be updated at a rate faster than you eye notices which is why you have to update at about 50Hz (you can sometimes get away with 35Hz). All graphics cards have to do this but instead of 8 bytes to update they have a whole screenfull which is why these graphics cards need a very fast graphics computing engine to do the job. Using a buffer separates the interrupt refresh code from the code that updates the buffer. This lets you optimize the interrupt code for fastest operation and ensures that the screen is constantly updated i.e. flicker free. The rest of the program updates only the buffer itself whenever it likes and it does not need to be particularly fast Note: For a true graphics system double buffering is used so that the display refresh data is taken from a buffer that is not being updated i.e. it makes the screen completely flicker free (the interrupt only uses data that is not half way through an update!)- this is only necessary for high end computer graphics systems and is not discussed in the projects. SurveyI know your time is precious the survey only takes half a minute to do...and as an extra thank you I'll take off 10% of the final price of the project set when you order (to do this just enter your email address when you complete the survey). |