seven segment led display driver for Steel Battalion gear shift.

[Robert.Ace]

Hello. I've been working on modding my steel battalion controller and in the process learn about electronics so that i can help anyone else that is interested in my gaming community. If you don't know Steel Battalion is a giant robot game for the xbox that came out in 2002. I just finished putting in a rumble mod that works perfectly (thanks to Resqeliune) and i had a few other ideas on where i want to go with the project.

What i want to do is add a seven segment, or 14 segment led display so i can get a cool display of what gear i'm in. As much as for practicality and coolness sake. I found two that i might like to use but i don't know how or what driver or circuit to use.
7 segment:
http://www.westfloridacomponents.com/LED094PD/7+Segment+LED+Display+Red+Numeric+LTS-312AR.html
14 segment:
http://www.rapidonline.com/producti...in)+Starburst+display&moduleno=29389#techspec

Here's what the gear shifter looks like.

It's pretty simple, just seven points with a single ground that's completed by shifting the metal contact points in the gear shifter.

Here's the gear shifter.

What i want to do is interface seven wires to the seven different gears. And each gear will tell the driver (or whatever i may need to do it) to display R for reverse and so on. That way i can do away with a counter. How do i accomplish this?

 

[Resqueline]

Glad to hear the rumble mod. works well now.

While there exists decimal to 7-segment encoders, you won't get N & R with those.
I think it may be easiest for you to use a diode matrix, 7 resistors (and 7 transistors - perhaps).
It'll take a lot of diodes but in each position you get to choose which segments are to be lit.
Please post a picture of the PCB - under the gear-lever - so I can see exactly how the circuit is made. (Single LED resistor, wires going to CPU?)

 

[Robert.Ace]

Thanks for pointing me in the right direction. I did a lot of research (so i would'nt ask questions i can find on my own) and i found this nice guide here:
http://www.instructables.com/id/TOD-Diode-Matrix-ROM-intro-7-segment-display/

I found all the part's i need to get and i'm just waiting for the mail.. I figure i can substitute his 8 pin dip switch for the gear shifter and draw my power from the gear shift board.

The schematic is slightly confusing but i guess simple. The power comes from the top lighting all the led's in the array. Except the diode is used to turn off an led in the array because electricity can only go one way through a diode, and thereby create a number.

Here's what the inside looks like. It's all just contact points that go to the main circuit board in the center block. The Led's are separate from the contact points in the gear shifter. They're controlled by the game system so they can light up when the game tells them to, or by shifting to that gear. I figure i can tape into either or and it'll work fine. There are some good places to solder wires on to.

Here's what the outside of the gear shifter looks like:

 

[Resqueline]

Yes, that's the way to do it (imho).
That circuit works by shorting out the LED segments (in a common-cathode display) that you don't want to light. It'll work without interfering with logic levels down to 1.5V, but it's kind of backwards and wastes a little more power than doing it like hotwaterwizard suggests here: http://www.instructables.com/id/TOD-Diode-Matrix-ROM-intro-7-segment-display/
I'd want to do it like that (but swap positive & ground and use a common-anode display). This solution however requires that the LED supply is not more than 2V higher than the logic supply.

 

[Robert.Ace]

Thanks, that's a lot clearer.