Gun talk - Sega Type-II IR Gun setup

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Howard_Casto:
Huh......

You know I might be more confused then before. Unless that sensor has some surface mount chips under that copper pad that sensor has a whole lot of nothing in there. Three pots would indicate three analog values of some kind.... X Y and Z? 9 pins could be the analog pins for each, but I'm just guessing.

I think the key to understanding what exactly this system does is to find that sensor in a regular old electronic parts catalog. It looks suspiciously like a light sensor with the IR filter tore off.

twistedsymphony:
I was thinking about this more last night and assuming the sensor is just a simple light sensor it's possible that it works on simple triangulation (or even biangulation since it's a flat surface) where it reads the intensity of each LED and uses that to calculate the pointer position. For that to work though the sensor would have to be sensitive to the light distance parallel to the sensing surface as opposed to perpendicular. Then I thought, I'm not even sure that's physically possible (then again I don't know much about light sensors).

Some searching I came across a type of IR sensor called a "PIR" sensor which is used in motion detection. these seem to have two sensing surfaces such that it can detect basic movement of light from one region to the next (hence motion detection). Adafruit has a good explanation: https://learn.adafruit.com/pir-passive-infrared-proximity-motion-sensor/how-pirs-work

that coupled with the LED array flashing in in sequence could very well be used to not only tri-angulate the position of the gun but also determine the angle at which the gun is pointed.

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EDIT: I forgot to mention the reason the sensor board has 9 pins is because 2 of them go back out to the trigger. so 7 come in from the Gun I/O then it has 2 that go back out to the trigger. I don't think the sensor needs the trigger information, I think they just did this for ease of wiring. Technically the sensor only uses 6 wires, at least one of which is a ground reference that is shared with the trigger.

I also don't believe there is any IC under the covered part of the board, I didn't want to pull it off and risk damaging anything but it looked like only thing under there were a bunch of surface mount resistors/diodes/caps (unsure since I only saw them from the side)

Howard_Casto:
Heh.... we must have been searching the same sites. The PIR sensor was my guess as well. The thing is, they aren't terribly accurate, especially when detecting a x and y value. I skimmed some patents and there are variants of these that have multiple sensors setup in a grid, but they don't resemble the part on the guns in the least.

Yeah I saw that resistor cutting off two of the pins last night.

I'll search Arduino forums later this evening to see if I can find one that shows a PIR sensor X/Y detection example.

This system might not be as hard to clone as it seems.

Xiaou2:
As far as Ive recall, a camera phone can see LEDs lit up.

The glass on the sensor appears to be a filter coating.

It might be a camera, that is filtered to see pretty much only the IR spectrum.

It might be that the LEDs are used to draw a constant border line.

And it may be, that something different happens to the LEDs, when the trigger is pulled.

It might be a dual sensor tech inside there.. with a camera, and a motion sensor.

There is more than likely a Patent that explains the tech in detail.

Other than that, use your phone to record what the leds do when the game is actually playing in-game.
Say "fire" as you pull the trigger... and see if the leds do anything different at that exact moment.

twistedsymphony:
If you follow the traces on the board the trigger wire never touches any of the rest of the circuitry, it just comes in one pin and goes out another pin to the trigger switch.

If they didn't wire it this way they would have either had to run a separate ground wire up for the switch or they would have had to have an extra ground wire coming off the sensor PCB anyway. which would have made the wiring in the gun a lot more messy.

I still think the sensor is way too thin to be a camera, every PCB mounted camera I've seen including those in modern cell phones is at least 3 or 4 times as deep as this thing is, and this particular board has been around since 1997. There's no way Sega perfected high-speed camera tech 20 years before everyone else and in such a small package that no one else has managed to make one thinner yet.

Good idea on the patent though.

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