EDIT: This thread follows my trials and mostly errors. Once everything is worked out, my findings will be organized into a more coherent thread.
Completed Logitech MOMO Racing hack information here:
http://forum.arcadecontrols.com/index.php?topic=113040.0 Skip down to the start of G27 tinkering:
http://forum.arcadecontrols.com/index.php?topic=112330.msg1202251#msg1202251Started tinkering with this last fall, but dropped the feedback motor and the tiny encoder wheel mounted to the back of it shattered.
I only found two of pieces of it at the time.
I've collected just about all the parts I need to revamp my driving cab with all arcade parts, so it's time to figure this out.
I'd given up on hacking a modern wheel that uses an optical encoder and ordered a Logitech Driving Force EX off fleabay.
The seller sent me a GT Force. It's still a pot-based wheel and I could have used it, but the cheap little thing only has 6 buttons.
Never buy anything used with a stock photo and description.
So that sent me back to the Momo Racing wheel that I started with.
I searched under the couch and actually found all the parts of the encoder wheel, but one. Superglued it back together.
It's not good enough to use, but it's good enough for testing. Good thing I hadn't vacuumed under the couch.
Anyways, haven't found much info on hacking a modern wheel and that motivates me to make this work.
The PITA part is that the movement of the steering wheel passes through 5 gears before it reaches the encoder wheel, so you can't just attach the encoder wheel to the end of your steering shaft the way you could a pot. I also want to get rid of the feel and sound of plastic gears.
I've still been too lazy to count the teeth, but did a little testing by counting the slots on the encoder wheel and how many revolutions it needed to make to turn the wheel lock to lock.
(I wouldn't rely on this being real precise, but in the ballpark)
So I figure if it needs 8 revolutions to move 270 degrees (which is 75% of 360 degrees),
it would need 10.66 revolutions to move 360 degrees. There is a stop that was removed and the wheel was actually moving farther than 270 degrees, so I'm just calling it 10 revolutions until I decide to count teeth on gears. So 10 revolutions of a 60 slot wheel=600 slots need to pass by the sensor per revolution if I want a 1:1 ratio with the steering wheel.
I tried printing some wheels on inkjet transparencies using available software, but it just couldn't get the resolution high enough.
Eventually, I ended up with a 7" diameter wheel that worked, but wasn't reliable or practical. For anyone else that tries printing their own encoder wheels, a dremel mandrel makes a good shaft and you can put a cut-off wheel on each side to stiffen up the transparency.
Now I'm thinking the next step is to find a self contained optical encoder to use in place of the logitech wheel and sensors.
I did find a company in Japan that is making wheels that use the original Logitech G27 board with one. They even show the encoder, but I couldn't find it's specs anywhere.
http://www.frex.com/gp/I'm having a hard time finding one with 600 pulses for a reasonable price. I'm thinking I'd be better off to go slightly lower resolution than higher because I could make up for it by adjusting the saturation in logitech profiler. But if the wheel on the screen reached its limit before the one in my hand, I'm not sure how to correct for that.
Would something like this work?
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=516-2023-NDHere is a pic of the opto board from the logitech wheel.
Would someone be willing to label the wires for me?
I looked at diagrams, but I can't tell if I'm supposed to be looking at the sensor pins from the top or bottom.
Anything else I need to know before dropping more money on parts to tinker with?