Hacking DC Controller w/ Hall Effect Sensors

[jerster]

Hey all-
Long time lurker here finishing up fabrication for a rotating control panel.
I'm interested in incorporating 2 DC controllers as one of my panels.  I understand analog console controls are not tried and true,  and am fully prepared to go digital, but the wifey would love some Sonic Adventure if at all possible.  The following excerpt from the FAQ page caught my eye and I was wondering if anyone has attempted it or not.  

Dreamcast
     The Dreamcast controller contains an analog thumbstick and analog shoulder (trigger) buttons.   On the original Sega pad, all analog controls are measured using Hall Effect Sensors.  Another detailed explanation of the Sega pad with hall effect thumbstick and trigger buttons is located here.  Since these hall effect ic's basically regulate a voltage between +5 (or 2.5v) and ground, its quite simple to hack them to digital controls.  All you do is ground out the one pin of the Hall chip. DC-to-Jamma has a pic describing which points to hack for the trigger buttons [the same could be done for the thumbstick].  3rd party manufacturers which make Dreamcast pads usually opt for the cheaper potentiometer approach to measuring analog input. [I don't recommend hacking potentiometers to digital controls unless you understand how they are used in the circuit. Most implementations use a centered voltage of +2.5v with +5v being the extreme to one side, and ground being the extreme to the other. Its still possible to wire a digital joystick to theses potentiometers, but you have to use a +2.5v source on at least two of the microswitches of the digital joystick (rather than ground). Hope that makes sense.]

I have original DC controllers and am curious to know whether anyone has tried to implement this, and even if they haven't whether they think it is feasible of not.  BTW, true analog is not important to me,  the only thing important is making the controller with w/ analog only games.

[Dave_K.]

If you have the original Sega pads, then hack the hall effect sensors.  The dc-to-jamma pic isn't working in the faq...look partway down the page here:
http://www.mameworld.net/pc2jamma/arc_dc4.html
Although the pic only shows where to hack the sensors for the triggers, you will hack the same sensor chip for each of the analog sticks axis'.   You could test to make sure the upper left leg they specifiy on each sensor is the one to hack by grounding that one out (wire a test connection from ground to that leg) to make sure it makes sonic run in that direction.

Just note, that Sonic (and other analog games) may become more difficult as you won't be able to make sonic walk to edges and stuff...it would be a full out run in any direction.  Try this out on the game first with the analog stick and if its still playable to you (with stick fully depressed in any direction) then you are good to proceed hacking.

[jerster]

Thanks for the input...I gave it a shot and it seems like it'll be ok.  Maybe not perfect, but it should get the job done, at least for the time being.

[crashwg]

What about hacking a hall effect joy to a DC controller?  They're still in production aren't they?

[gnateye]

for my dc cab i just have all the digital controls on the control panel, then i used 2 control extension cables from the dc to 7/8" holes i drilled on the sides of the panel for other controls like guns, fishing rods, dance pads and of course regular controlers for either 4 player games or games like sonic that need analog controls. its not perfect, you have to use theregular old controller sometimes, but trying to play analog games with hacked analog to digital controls is a huge drag, you lose ann your "finese" when trying to play these games which kills the fun. in my opinion of course.

good luck, i would love to see someone hack the analog to analog sticks, that would be cool, but prolly expensive