Monday, February 05, 2007

Arcade Displaya Hater

Ok, can you really have a multi-functional arcade machine / Jukebox without a display. Didn't think so. Since the whole machine is pretty much scratch built I didn't think it appropriate to throw some off the shelf LED matrix display up there so I decided to whip up something on my own. Here's how it began. Since the overall theme for the box is old school meets modern, I needed to figure out a way to introduce a dash of late model style to some outdated tech. As luck would have it, I already had just the thing in my parts box. Maxim's multi-segment LED character driver IC (MAX6954) would do just the trick. The only thing better than some retro alpha-numeric action would be rockin a few Nixie tubes. And don't think I wasn't considering it. I still beam like a proud father at the wiring job. Though, bet your bottom dollar that I'll be makin some printed circuit boards if I ever decide to wire up 84 LED's again.
At the moment, the display only cycles through a pre-determined sequence of words and symbols but it's connected to the arcade's PC via the serial port so it'll eventually (sooner than later) display high scores and game titles. Neat huh? I dropped off some design elements halfway through construction so I think I would have approached this differently had they not been there at the beginning. Being that I was initially constrained by size requirements, the character spacing is a little closer than general standard practice and I didn't utilize all of the LED driver chip's available characters. But I'm still pretty happy with the way it turned out so I can't complain too much. Wanna see a video?

Friday, January 26, 2007


Mighty Giant Panda, your day is almost afoot! Can you see the shadows that mark the twilight of humanity? Our numbers have never been as high but our collective eye has been led astray for many ages. What arrogance are we that call you "Bear" and fawn over your fuzzy fur. I've been watching you. Listening... I feel your power, I prostrate myself before it in awe.

I know these humans, I have gained their trust. I walk among them freely but not without prejudice for I am one of them but my spirit is Panda. However, trust not. But allow me the opportunity to earn it in this our upcoming battle for freedom. I am allied with the Giraffe and they call me Battlesnake, sachem of justice, holder of wiffle, usurper of that which needs usurption. They are not the most eloquent of species but they are strong and together, we can not be stopped. Upon the backs of our long necked brethren we shall ride. The bi-peds will be stunned by the paralyzingly adorable spectacle before them. Dark sulky eyes and fluffy white tails will be replaced with tooth and claw and just as they realize what is happening, victory will be ours. San Diego... sacked. Antwerp... sacked. The Bronx... sacked. Sydney... sacked. Berlin... Sacked!

We'll see how much they like chewing on bamboo. Are you with me?

Tuesday, January 23, 2007

Le signe est fait. Translation... "sure took me long enough."

"Bar Sign" project is finally complete. I think my sister liked it although I did see some gaps in her enthusiasm during the unveiling. I believe they were failed attempts at comprehending my fascination with LED's. She was right to be confused, a tiny blinking light can only giddify the most stout of geeks. I hope she enjoys looking at it as much as I enjoyed building it.

Speaking of construction, allow me to front you some details. The black wooden shadow box frame measures in at around 20"x8" and holds two pieces of hand etched Plexiglas panes illuminated by six tri-colored (RGB) high intensity LED's. Quite a mouthful huh? That's not the fun part. To drive all the the color combinations possible, I used a
Microchip PIC16F676 microcontroller and a Maxim MAX6957 LED driver to do all my dirty work. I'm still trying to decide why I wrote the firmware in assembly. Sometimes those things harder to do aren't always worth doing.

This is what the guts of the project look like. Not the prettiest of designs out there but it could have looked worse if not for using plain ol phone wire to hook up the lights. Its four conductors were perfect for each four-lead LED.

Want some theory? I'll let Wikipedia handle the bulk of the work for me. In a nutshell, I vary the intensity of red, green, and blue light to create any color I want. I direct that light through the side of each pane of Plexiglas and it escapes only where I have etched it. I didn't go too crazy with the lighting programs. I only wrote five and they can be cycled through by pushing a button on the side of the frame. I also included a control knob so you can pick your own color if the appropriate program is selected. But enough of this talk, here are some pictures and a video.