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Author Topic: Pole Position Gas Pedal - Hooking up a Potentiometer?  (Read 6623 times)

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JLR2000

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Pole Position Gas Pedal - Hooking up a Potentiometer?
« on: September 12, 2002, 11:44:29 am »
Hi Folks, me again...

I'm hooking up a gutted Pole Position cab to a PC running dos mame.  I noticed that the gas pedal is not a switch but a "pot" (potentiometer).  Can I interface this the same way as I would a normal switch?  I'm hacking a mouse for the x-axis (steering) and the 2 buttons for 1. shifting (switch) and 2. gas (pot).  I've never worked with a pot before so I'm in new territory here.  Any help or advice would be appreciated. Thanks! :)

Lilwolf

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #1 on: September 12, 2002, 12:04:08 pm »
Assuming its a 5k pot (and most arcade pots are) there is two solutions (assuming you want to keep it pot based and not hack it all up)

1) replace it with a 100k pot and hack it into a gameport

2) Buy a microsoft dual strike joystick that uses a 20k pots (but it only turns 1/4 rotation (effectively a 5k pot)...  This btw, is 1UP starwars hack.  

Other solution... put a leaf switch at the bottom and have it on/off.  works for most games, but not as nice.

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #2 on: September 12, 2002, 12:23:18 pm »
Thanks Lilwolf-

I may just put a switch in there.  I'm only putting Pole Position and PPII in the cab, so it shouldn't be a big deal.  Your other options sound like too much effort just for two games.  Thanks for the input...

Just for the heck of it, what would be the effort/cost of replacing it with a 100k pot? Where would I get it (radio shack?)  I will be putting a hacked gravis gamepad in for some other controls (coins, pause, or whatever) so this is possible. How do I hook that up then, is it just a two wire deal like a normal switch or more involved?   ???

Thorn

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #3 on: September 12, 2002, 02:46:13 pm »
The 100K pot will cost about $1.50. Check out Lews Wheels for how to connect it to the game port. Look in the controls section here and then steering and you will find the link to Lews wheels.  Someday I'll hook up my triple wheels 7 pedals using his instructions.

   

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #4 on: September 12, 2002, 04:39:39 pm »
Basics on pots: there are 3 terminals on a pot, you either hook the wire to the left and center or the right and center terminal.  On one set the pot will read X (5k, 100K) ohm when fully CCW and short (0 ohms) when fully CW.  On the other set, the pot will read 0 ohm when fully CCW and X ohms when fully CW.

Information on what pots look like and wiring them up to the gameport is available at http://www.gunpowder.freeserve.co.uk/wheels/wiring.htm

I try to avoid the gameport as it always has calibration problems, but it's the easiest way to hook it up and still have the functionality of the pot.

Also, I have some driving pedals with 50K (?) pots in them and I know I could just hook them up to an I-PAC and they would work as switches.  (On-Off only, but I usually keep it floored in driving games anyways).  You MIGHT be able to wire the pot to the gamepad/mouse and have it work as an on/off switch.  I would try that as it's probably the simplest option.  As long as you solder properly, worst case is the 5K will be read as a short and the switch will be closed all the time.
 
Also not sure if PP had an HI-LO shifter, or just on/off, might need two switches.

Info on replacing arcade controls with pots to connect to gameports is here: http://www.arcadecontrols.com/arcade_jude.shtml


Just for the heck of it, what would be the effort/cost of replacing it with a 100k pot? Where would I get it (radio shack?)  I will be putting a hacked gravis gamepad in for some other controls (coins, pause, or whatever) so this is possible. How do I hook that up then, is it just a two wire deal like a normal switch or more involved?   ???


Radio Shack, should be $5-10 dollars or less (probably less).  Just two wires as above.
It's not what you take when you leave this world behind you, it's what you leave behind you when you go. - R. Travis.
When all is said and done, generally much more is SAID than DONE.

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #5 on: September 12, 2002, 04:56:22 pm »
TigerHeli-

THanks for the info and the links!  I'll look into what my easiest option is.....I'm like you in that I keep the gas floored during all driving games anyway....

FYI-  The shifter is definitely one switch, it is activated when you shift high or low.  Looking at the controls for PP verifies that there is only one input for "SHIFT".  Luckily all the original controls are still in the cabinet.  I'll dig into the gas pedal pot maybe tonight.  Is it safe to assume from your post that I can try the existing pot with a mouse/gamepad hack without fear of ruining something?  I don't want to fry my computer over the one pot if that's possible.  Thanks again!!

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #6 on: September 12, 2002, 11:36:04 pm »
Okay, maybe I spoke too soon....

There is only one switch on the shifter knob, which I hooked up to my mouse button 1.  Unfortunately, it acts like just 1 switch, I have to "double" shift to get it to register. For those of you who don't know, the PP shifter has LOW and HIGH. LOW releases the cherry microswitch, HIGH depresses the switch (and holds it down). Did the original game read the switch as "pressed" or "not pressed"?  I don't think MAME version of PP works this way.  Any suggestions or anyone know something I don't ??   ???  THANKS!

Mr. Do

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #7 on: September 13, 2002, 12:27:00 am »
I had your same problem , as I just won a PP shifter on eBay, and was perplexed as to what to do.  You have two choices:

1.  Install a second microswitch.  The first thing I did was take mine completely apart to see what I could do with it.  You can install a second microswitch and actuator so that a switch is hit each time you shift, then set both of those inputs in MAME so that whichever you hit shifts gears.  You just need to make sure that the shifter is in LO whenever you start MAME.  Only thing, though, is you can't use a standard microswitch that you find on Happ buttons/joysticks with the same size actuator, as the switch doesn't stick out enough.  You either need a longer actuator or longer switch (if anybody knows where to find this switch, it would be greatly appreciated).

2.  Change the MAME source.  I had asked this question on the MAME board, and stephh gave me a reply.

Quote
There is no warranty that it works (I can't test this !), but try to change this line in 'polepos' and 'polepos2' INPUT_PORTS definitions :


   PORT_BITX(0x02, IP_ACTIVE_HIGH, IPT_BUTTON1 | IPF_TOGGLE, "Gear Change", KEYCODE_SPACE, IP_JOY_DEFAULT ) /* Gear */

to :

   PORT_BITX(0x02, IP_ACTIVE_HIGH, IPT_BUTTON1, "Gear Change", KEYCODE_SPACE, IP_JOY_DEFAULT ) /* Gear */


I haven't tried that one yet, so I'm not sure on it yet.  

Hope this helps.


RELAX and just have fun.
Remember, it's all about the games.

Mr. Do!'s Arcade

SirPoonga

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #8 on: September 13, 2002, 01:04:15 am »
suprised robin hasn't replied.  hook up the pot, use the gas pedal and analog mame!

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #9 on: September 13, 2002, 01:19:56 am »

I had your same problem , as I just won a PP shifter on eBay, and was perplexed as to what to do.  You have two choices:

1.  Install a second microswitch.  The first thing I did was take mine completely apart to see what I could do with it.  You can install a second microswitch and actuator so that a switch is hit each time you shift, then set both of those inputs in MAME so that whichever you hit shifts gears.  You just need to make sure that the shifter is in LO whenever you start MAME.  Only thing, though, is you can't use a standard microswitch that you find on Happ buttons/joysticks with the same size actuator, as the switch doesn't stick out enough.  You either need a longer actuator or longer switch (if anybody knows where to find this switch, it would be greatly appreciated).

2.  Change the MAME source.  I had asked this question on the MAME board, and stephh gave me a reply.

Quote
There is no warranty that it works (I can't test this !), but try to change this line in 'polepos' and 'polepos2' INPUT_PORTS definitions :



J_K_M_A_N

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #10 on: September 13, 2002, 07:55:39 am »
I am at work so I can't try this but, can't you just set up mame to use 'not button 1'. You can if you use 'button1 not button2'. I am not sure if you have to have another button when you use 'not'. That might not make any sense to anyone but it is 7:00 and I am not quite awake yet. I will check when I get home unless someone actually understands me and can check it out.
Good luck.

J_K_M_A_N

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #11 on: September 13, 2002, 11:09:32 am »
J_K-  

I can test it, but I'm not sure how to setup 'not button 1".  How do you input the "not" condition? Also, I'm not sure how this would work, since the switch in the controller is only 1 input, open or closed.  From what I know, when you press the switch the circuit is  momentarily closed (or opened depending on how you wire it).  It looks like for PP, the game could distinguish between the circuit being open or closed, and changed from LOW to HIGH based on those conditions, not based on if the circuit was momentarily closed.
i.e. open   = LOW
      closed = HIGH

I hope I'm explaining this okay.....

J_K_M_A_N

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #12 on: September 13, 2002, 12:49:53 pm »
Well, let me start off by saying I doubt it will work but it is worth a try. I am not sure how the settings are for PP in mame. If it has 1 switch for low and 1 switch for high then you could try the following:
set low = 'button 1' - just press the button once
set high = 'not button 1' - press the button twice
I don't know if you can just have 'not button 1' by itself. It may have to be 'button 2 not button 1' in which case it wouldn't work.

Like I say, I doubt it will work but give it a try. I wish I were home so I wouldn't make a fool out of myself. I would have tested it and probably kept my mouth shut. Good luck though.

J_K_M_A_N

Mr. Do

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #13 on: September 13, 2002, 05:18:36 pm »
Well waddya know, it WORKS!!  Just tried the new compile and it should work perfectly!!  When the switch is open, you are in LO gear, and when the switch is closed, you are in HI gear.  Way to go stephh!!  Can't wait til this thing's done!!


RELAX and just have fun.
Remember, it's all about the games.

Mr. Do!'s Arcade

JLR2000

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #14 on: September 13, 2002, 05:41:19 pm »
GREAT NEWS!  I haven't had a chance to compile it yet.  I've gotta get setup for dos compile, (I've been compiling MAMEW since it came out).  Thanks for sharing the info Mr. Do!

 ;D SUCCESS  ;D

I was able to make the changes, compile and test....it works perfectly.  Mr. DO....thanks for sharing the info here and please pass my thanks on to  stephh!
« Last Edit: September 13, 2002, 11:23:11 pm by JLR2000 »

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #15 on: September 14, 2002, 11:19:52 am »
I am currently building a racing panel for my homemade cab, and have run into the same issues.

For gear shifting w/ a pole position shifter, I think I may have another option using my Hagstrom ke72 encoder.  
The ke72 can be programmed so that a keystroke is generated when an input is released.   I plan on configuring it to send the same keystroke when the shifter switch is pressed and released.  The only problem, like DO!'s dual switch solution, is that the shifter will need to be in the 'LO' position before the game starts.  If this gets annoying, I'll probably do the recompile thing.

As far as pedals are concerned, I'll will be using a Super Offroad pedal, and a Happ "flat pedal" (part no. 50-8195-01).  They both have potentiometers, but I will be retrofitting them with actuator plates and "roller" microswitches I ordered from Happ.  Since the pedals already have mounting holes for the switch/actuator, I hopefully can get by w/o drilling or cutting.  If I get ambitious, I may reinstall the pots and try the dual strike hack later.
Also, I will probably have one pedal "slideable", so I can have the pedals close together for a gas/brake combo on single player games, and farther apart for multi player games like Super Sprint and Super Offroad (my panel has 2 wheels, btw).

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Re:Pole Position Gas Pedal - Hooking up a Potentiometer?
« Reply #16 on: September 14, 2002, 11:23:13 am »

Also, I will probably have one pedal "slideable", so I can have the pedals close together for a gas/brake combo on single player games, and farther apart for multi player games like Super Sprint and Super Offroad (my panel has 2 wheels, btw).



Clever idea on the "slidable" pedal .  . .  8)
It's not what you take when you leave this world behind you, it's what you leave behind you when you go. - R. Travis.
When all is said and done, generally much more is SAID than DONE.