Making a scoreboard

[Calder]

Hi.
I'm trying to research if it would be possible to make our own scoreboard for our inlinerink, instead of paying 5-10k for one.
I would like to control it from my computer (laptop), only got USB but I guess I could buy another comp. for this project...

Mostly looking for links to get me started with using LED 7-segments and controlling it from computer, but any other help would be appreciated! :-)

Building the scoreboard I'm thinking about would require 32 numerical digits (32*7=224 segments), plus an additional 3 segments for colons and two 1's for the results (so I can share the ScB with basketball, won't see scores over 100 for inlinehockey..). Would also be great to later add an alphanumeric marqee, but not a must...

So any help would be appreciated, so I can get the county to pay for rebuilding/refurbishing the rink instead of buying a scoreboard! ;-)

Thanks in advance!

[Rob]

Welcome to the boards.

How big? If it's at all possible to use a general-purpose LED display, you probably will get to the payoff quicker and cheaper that way. Plus it's alphanumeric from the jump.

The seven-segment drivers I'm familiar with (7447) seem to be discontinued. That doesn't mean you can't find any, but it may be a sign there's a better approach now.

[Calder]

For now, just a small version using ready-to-buy LED digits (7-seg). But if it works the way I want to, then the total size of the enclosure would be something like 2x1 meters...
But I need to find some way of controlling 32 numerical digits first, and learning how to do that... A little hack to do that would be using an I/O board with 256 outputs. :-)

[justDIY]

visit:

www.maxim-ic.com

read about multiplexing and charlieplexing ... Maxim's innovative charlieplexing method allows a designer to use fewer control lines in number or alphanumeric displays.

Maxim also has a LOT of chips dedicated to driving 7 segment displays, along with evaluation boards for those chips, so you can see it in action.

If you want to reinvent the wheel and build something rather than go prefab (experience tells me prefab will cost a lot less), you'll need to learn about microcontrollers, multiplexing, serial communication, just to desribe the tip of the iceberg 

Alternately, you may still be able to find old fashioned (manual) 7 segment drivers from surplus shops, but you will still need some method of generating the data they require (usually BCD or Binary format), which means a parallel printer port at the very least, and then you're looking at a mountain of software to make it happen.

I don't understand how you come to 32 digits for a score board.

I see 3 for visitors, 3 for home, 4 for the time ... so that is 10 digits? or maybe 12 digits if you wanted hundredths of a second on the time

In summary, you either want to watch the auction sites for a good deal on a used pre-fab display (maybe it has a few burnt out leds you can replace)... or you want to visit www.maxim-ic.com and read up on building your own.

The MAX6954 / 6955 looks like the chip you need, it contains everything to run up to 16x seven-segment  numberic displays or 8x fourteen-segment alphanumberic displays, by everything, I mean, it even includes a font table and character generator - you feed it  number or alphanumeric data, and it displays it, that sure beats the olden days.

http://www.maxim-ic.com/appnotes.cfm/appnote_number/1131

[Calder]

Actually 33 digits... The scores require 2 per team (keeping the hundred digit either on or off), clock 4, period 1. But since it's hockey I also need 4 sets (2 per team) of penalty times with playernumber... 6 digits per set...

Maybe it will be cheaper to buy when it comes to the big scoreboard, but it would be fun to try to build a small prototype using 12mm digits and write a program for it...

And thanks for the link to the MAX6954, looks like I have to read up on it. Saw that it could be daisy-chained, but don't know if the second will only act as a slave or if they can be seperate.