GUN4IR - The Ultimate 4 Points Lightgun System

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Howard_Casto:
I'm pretty sure the logic board is taking the 12 readings it gets from each led and processing with via calculations those readings into the analog signals you mentioned, so no, the calculations ARE necessary unless you know something I don't. It actually says so in the first sentence of the page you linked to. The reason that it does this is so that the gun operation is completely separate from the game pcb, so the gun tech can be swapped out as the years roll on and still be used as a replacement for older games. The calculations might be rather complex considering they have a dedicated cpu just to do them.... then again those boards are pretty old and a beefy avr might be just as powerful. I would think that in the gun would have four ir sensors so that the difference between both x (left and right sensors) and y (top and bottom sensors). The thing is it looks like there are only two. I'm lost on that one as I can't figure out how the vertical position could be detected that way. The multiple led boards might have to do with the resolution. It could be that the horizontal resolution of the sensor is rather poor, so it has to be checked a section of the screen at a time. That would explain the 20ms response time and the leds turning on in sequence.

We might be able to dumb it down... buy four light sensors, throw them in a gun and put four leds around a screen. We really need someone that knows about these types of sensors.

Zebra:
It's true that the system is stand-alone but what it outputs is no more complicated than an analog joystick. You can actually use an analog stick to control Sega type 2 gun games. All the work to translate voltage to coordinates is done on the other side. You need to physically tell windows which voltages = the screen edge.

It also relies heavily on the screen out feature (digital button 3 on my UHID) to know when to stop tracking. It loses all accuracy when I disconnect the screen-out cable.

The gun sense boards are big but most of the space is taken up with voltage regulators, pots and ports. The actual IC chip is fairly small and I am sure you are right that a modern AVR or Arduino could do the same and then some.

I'm wondering if the IC chip from the gun sense boards has already been dumped for one of the emulators. If it has, would someone with your programming knowledge be able to see how it works?

Howard_Casto:

--- Quote from: Zebra on December 30, 2019, 02:57:12 pm ---It's true that the system is stand-alone but what it outputs is no more complicated than an analog joystick. You can actually use an analog stick to control Sega type 2 gun games. All the work to translate voltage to coordinates is done on the other side. You need to physically tell windows which voltages = the screen edge.

It also relies heavily on the screen out feature (digital button 3 on my UHID) to know when to stop tracking. It loses all accuracy when I disconnect the screen-out cable.

The gun sense boards are big but most of the space is taken up with voltage regulators, pots and ports. The actual IC chip is fairly small and I am sure you are right that a modern AVR or Arduino could do the same and then some.

I'm wondering if the IC chip from the gun sense boards has already been dumped for one of the emulators. If it has, would someone with your programming knowledge be able to see how it works?

--- End quote ---

Unfortunately I don't think the chip has been dumped. Mame just reads the x/y values from the proper address and I always wondered how exactly they got x/y from a light gun game but now I know. I need to check one of these nerdy sites that do Arduino projects and see if someone has fooled with light sensors to detect ir leds. If doing it from scratch finding an appropriate sensor would be the first step.

thet0ast3r:
Ok, Zebra. Here we go again.

You removed the IR Shield from the 4 sensors on the tiny pcb that is in the nozzle of the gun. What you also removed, is a rectangular ( maybe/probably square ) iris ( some plastic cap with a square hole in it).
This plastic cap has its opening in the middle of these 4 sensors which are just 4 flat photodiodes. If you shine a light on these photodiodes with the cap on, depending on which angle you shine, the amount of light that hits each individual sensor varies. if you happen to point the light straight at it, all 4 sensors get the same amount of light. The sega ir II system uses this difference in measured brightness to calculate the ANGLE of ONE* light source. This is why the IR diodes mounted on the screen are connected to the pcb, and not just to some power source. The ic`s of the gun system are synced, so that the gun can read all angles of the ir lights ONE after another. With this information ( all angles of all light sources) (and the position of the light sources which is obviously known since they are fixed) the system calculates its 6 degrees of freedom in relation to the screen, and converts the screen coordinates to 2 analog outputs for x and y. It also knows (just like ems topguns) when it is pointed offscreen, and returns that aswell.

I am 99% confident this is the way the ir II system works.

* I do not know how exactly they deal with outside light sources. Maybe they just read the photodiodes while no light is active, and subtract the intensities.

Zebra:

--- Quote from: Howard_Casto on December 30, 2019, 03:22:02 pm ---
--- Quote from: Zebra on December 30, 2019, 02:57:12 pm ---It's true that the system is stand-alone but what it outputs is no more complicated than an analog joystick. You can actually use an analog stick to control Sega type 2 gun games. All the work to translate voltage to coordinates is done on the other side. You need to physically tell windows which voltages = the screen edge.

It also relies heavily on the screen out feature (digital button 3 on my UHID) to know when to stop tracking. It loses all accuracy when I disconnect the screen-out cable.

The gun sense boards are big but most of the space is taken up with voltage regulators, pots and ports. The actual IC chip is fairly small and I am sure you are right that a modern AVR or Arduino could do the same and then some.

I'm wondering if the IC chip from the gun sense boards has already been dumped for one of the emulators. If it has, would someone with your programming knowledge be able to see how it works?

--- End quote ---

Unfortunately I don't think the chip has been dumped. Mame just reads the x/y values from the proper address and I always wondered how exactly they got x/y from a light gun game but now I know. I need to check one of these nerdy sites that do Arduino projects and see if someone has fooled with light sensors to detect ir leds. If doing it from scratch finding an appropriate sensor would be the first step.

--- End quote ---

That's a shame although I guess it's not a surprise as one of the key points of emulators is that they allow you to use regular PC controllers for old games.

I'll ask the guys on the Arcade Projects forum. A lot of them have type 2 gun cabs and the means to dump chips. It's possible someone dumped them to make replacements.

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