Saturday, August 6, 2011

A picture's worth...

You can see it in very crude motion including a crude pong-isch game on Youtube.

What you see above is a PinLED display driven directly via the Arduino microcontroller. I was going for a plasma screen first but they need a lot more power, four different voltages from -115VAC to 115VAC etc. The PinLED hooks up directly to +12VDC which is a much more convenient level. If you're also worried about the environment or electrical bill, the PinLED is also preferred as it stays under the RoHS law.

The current display code draws a frame of information, in which the designer/programmer (me) fills with data. The current supported commands are just 3-5x5 letters and numbers being printed at any x,y coordinate. The final code will of course feature animated images etc. It's actually supported already, I just need to find a tool (or code one myself) that converts regular images to byte arrays that can be used in the code. 

As always, the DMD pixels are just on/off so different shades are created by lighting the various pixels for a different amount of time. I've yet to find a suitable method for this but the idea is that the final version will feature "multicolor" images. 

At the moment that picture (and video) was taken it ran at about 5.5 ms, i.e approx. 180 Hz. The current code revision runs at about 0.5 ms meaning it's too fast for the refresh rate of the screen... Therefor I need to slow my code down to push the refresh rate below 200 Hz (the maximum). 

It's a good day for a programmer when the main problem with the code is that it runs too fast!

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