7-segment displays and data that drives 'em

[Bham78]

Hi everyone,
I have worked with some lite electronics before, but now I'm probably in over my head and on the line to produce.
I am part of a Drag Boat Race Club and we are going to build a Scoreboard. It will display the ET (elapsed time) and MPH for the 2 racers running. It will be 5 ft tall and 30 ft long on a floating platform.
I have been researching using 7 segment displays and using super bright LED's. I will probably be using the Moto- 14489B IC display driver.
The company that we bought the computer from is going to supply the new code to drive the segments. But I have to get the data to the Scoreboard.
Now here is the rub. because the race takes place over 1/4 mile the Scoreboard is typically 1000 ft from the computer. I am concerned that the length of the data cable is going to degrade the signal to much.

So my question is what is the best way of sending the serial data to the controller?

Please feel free to post here or e-mail me at Bham78@aol.com.


Thanks
jim

 

[kinjalgp]

For your case you should use RS485 serial data transmission which can work upto a distance of 1.2 kilometers. For converting RS232 signals from computer to RS485, ready-to-use converters are available or you can build your own using converter ICs from www.maxim.com

 

[Bham78]

Thanks K,
I have also looked at the Maxim drivers. After your post I have gathered a lot more info from the Maxim site. In fact so much good info that makes sense, that I will need a few days to digest it all.

I know I am going to run into other problems and after browseing some of the other topics, it appears I have found the ANSWER MEN.

Jim

 

[pebe]

Hi Bham,
A 5' x 30' panel is a big panel to light up with 7segment displays. I am assuming if its's a floating platform it's on some sort of raft. How are you going to get the power there? Will the data cables be above, or in, the water?

 

[kinjalgp]

Does it really going to matter whether your cable is insdie water or outside if you are going to use a good quality shielded PVC cable?

 

[Dean Huster]

A thousand feet!! Wire? NO!!!

If this is a permanent installation, well, 1000 feet is doable, but still a hassle to lay and maintain. I'd consider an RF link, especially if you have to pick all this stuff up after the event is over and lay it out again next time.

Dean

 

[kinjalgp]

I gave you the wrong link above. The correct link is www.maxim-ic.com
Sorry for the inconvenience.

 

[pebe]

Does it really going to matter whether your cable is insdie water or outside if you are going to use a good quality shielded PVC cable?

It's hardly the sort of application where you would use screened cable - probably a twisted pair. And if you get water between and around the pair then, yes, it will make a difference. Water will increase the capacity between the wires - and it's a pretty lossy dielectric. Been there, done that, thought it would be OK - caught the cold!