Changing 360 analog triggers to digital (on/off)

[Kyosho]

I'm trying to get the analog triggers on an Xbox 360 controller to work like a normal button. Rather than the analog of somewhere in between. On episode one of the Benheck show (110ish), Ben shows you how to do it, assuming you kept the pots (and perhaps glued them in place so they don't rotate). However, I desoldered mine because there wasn't space for them. Well, I've moved houses since then and have no idea where they could be. However, I know there is a way to do it without the pots, I'm just not sure how.

I searched here (nothing) and BH (nothing) and finally on the ArcadeControls forum I found reference to it. I figured they'd be accustomed to using 360 controllers for MAME cabinets and I was right. But it appears they usually just ignore the triggers entirely. However, I did find one thread on the subject. Problem is, there are two solutions given, and I'm not sure which is right:

There are three pins on the pot/pad. If you look at the pad as if you are holding it, bridge the bottom two pins with a 10k resistor. Attach a ground wire to the bottom pin and attach the NO terminal of the buttons microswitch to the top pin.

One is to remove the potentiometer if you do the best thing to do is solder 2 10K resistors to the contacts so that they won't register as open. You then solder a wire to the middle contact as your signal wire and then wire the ground wire to any common ground on the controller.

Can anyone here weigh in on this? I tried registering there, but they apparently like to approve new members manually and I haven't been approved to post there yet. I figure some one here has done something like this in the past. Perhaps with the Dreamcast, but every DC portable I found had the triggers intact.

 

[grossaffe]

Okay, so that right there is a potentiometer schematic. pin 1 is input, pin 2 is output, and pin 3 is ground. That arrow right there slides the output nearer to pin 1 or ground, changing the amount of resistance on each side. What you want is a switch that will change which essentially change which side of the resistor you attach the output.

What I would do is use a SPDT Button and a couple resistors (if the 360 potentiometer has a minimum resistance of 0, then you only need 1 resistor).

I made a schematic, but its taking some time to upload, so I'll describe it best I can until I can post the schematic.

Vin = Node A
data out = Node B
ground = gnd
R1 = min resistance
R2 = max resistance - min resistance

R1 connects to Node A and Node C
R2 connects to Node C and gnd
Button Input1 connects Node C
Button Input2 connects to gnd
Button output connects to Node B

Note: if the minimum resistance is indeed zero, you can replace R1 with a short-circuit.

also, for future reference, this kind of thing may be better to post in the Random Electronics Questions forums, since really this deals with general circuit design more than the actual specifics of a 360. I don't usually browse the console forums, but I pop into the REQ to see if there's anything I can help with.

edit: ahh, here we go.

top node is Vin, bottom is ground, and side is data out.

Its entirely possible that the other schematics may work in this particular implementation (well, I'm not sure what's going on with the second one as there's no switch involved there...), but my schematic should perfectly emulate the extremes of the Potentiometer. I read that the max resistance is 10k ohms. I think you could get away with just shorting R1 and making R2 10k ohms.

Of the schematics provided, I think the first one could probably work as well, assuming pin 1 is the Vin, pin 2 is ground, and pin 3 is data. When the switch is closed (button pressed), you've got Vin going directly to the data, and also through the 10k resistor to ground. However, when the switch is open, you've got the data line is only connected to the ground and 10k resistor. The controller's logic will probably be able to handle that.

My schematic should perfectly emulate the potentiometer, but the drawback is it requires a SPDT button. The first schematic you provided should probably get the job done and only requires a SPST button, but I'm not entirely positive it will work.

 

[Kyosho]

Ah, I'm afraid I didn't see this post earlier but I eventually figured it out. Thank you for all the effort.

For future reference (in case anyone searches for it), there are multiple methods implemented in 360 controllers. Not only do they vary by brand, they vary by model. The best place for 360 controller hacking I found was the Shoryuken forums. Specifically their Tech Talk forum. People make arcade sticks out of 360 controllers there (for use with Street Fighter, obviously), and there's a large wealth of information there.