Friday, March 27, 2015

Optical Sensor installed in Qanba Q4 Fightstick

A hobby of mine is to use small arcade style controllers to play fighting games. I'm pretty decent. Anyways, I recently found that an optical sensor existed that could replace the microswitches in the joystick. The microswitches act as a mechanical sensor that detects movement on the joystick (up, down, left, right, and the corner combinations). These are all well and good, but having a silent joystick that is slightly more precise is more my style. The only complication is that the special optical sensor required a power source and while I could have soldered something directly to the circuity inside my Qanba Q4, I wanted the option to switch between the optical sensors and the microswitches without having to solder and unsolder every time between the two.

So I designed a little pcb that would facilitate as a USB to power hub. The intention was to make the cord modular from the fightstick so instead of having an always connected power cable, the cable could be removed completely. Also, the power for the Qanba pcb and the optical sensor would connect to my pcb and could be disconnected when switching from optical to microswitches.



So this is the board. Super small, super simple. Sadly, I was not able to use it. Not because it didn't work, but because I did not have the proper connectors to attach to the Qanba pcb. Dupont cables didn't work, molex didn't work, and the do-it-yourself wire connectors that are in the instrument room here at Purdue didn't work either.

I'm under the impression that the wire connectors that Qanba uses are special or at the very least not very common. While iteration ALPHA didn't work, I plan to go back with iteration BETA to hopefully use my design, but because I wanted to use the sensor last night I had to improvise.






I'm not sure if anyone knows the name for these particular connectors, but if you do please email me because I don't know what to search for.

Also because I was really annoyed that every photo of the Qanba Q4 pcb was taken by a potato, here is a better photo of it with no modifications and I've unhooked the microswitches along with the power connector from the USB cable.









Here is my improvised cable soldering. I was really hoping to avoid soldering so that I could keep it simple for others to implement, but c'est la vie.

It's kind of a bad photo, but the main points to take from it is that I'm pulling 5 volts (red) and ground (black) from the USB power cable. The other four colors are direction inputs for the Qanba pcb.





So here is the final connection scheme. I recycled the Sanwa microswitch cable that was already being used with my JLF stick (the joystick itself) for the directional inputs, and the important part is that you can see that the power and ground connectors are soldered to the USB power cable.

Everything worked out a lot better than expected after I already gave up on finding a proper connector at 11:30 pm. Minimal soldering and the optical sensor works very well. I don't expect there to be any questions, but if you're looking at this in the future four years from the date of this post or something like that, feel free to send me an email. I'll probably respond unless the internet stops being a thing in the future.



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