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Main => Main Forum => Topic started by: sgould on September 01, 2017, 05:20:14 pm

Title: Using arcade light guns with MAME
Post by: sgould on September 01, 2017, 05:20:14 pm

I have a Sammy trophy hunting cabinet with jamma harness. Is there a way to use the 2 sammy shotgun light guns with a MAME setup?

Thanks for taking the time to look and answer this.

Title: Re: Using arcade light guns with MAME
Post by: lilshawn on September 01, 2017, 06:54:40 pm

short answer, no

longer answer...

The logic to determine where the optic gun is pointed is on the host hardware, not the gun itself. There is no standard, but they all work basically the same way.

1. The gun does not emit light but senses the light from the monitor screen. The gun always sees a spot on the screen where it is pointed and gives a negative going 5 volt pulse to the game whenever that spot is illuminated. The signal is a pulse train of about 7 pulses, separated in time by whatever the horizontal frequency is, every time that particular spot is refreshed. (Only one pixel is illuminated at a time, but it's so fast it looks to the eye like they are all illuminated all the time).

2. The game knows which pixel on the screen is illuminated at any given time as it displays each video frame.

3. If the game gets a signal from the gun optics when it aims at an illuminated pixel and it knows which pixel is illuminated at any given time it therefore can determine where the gun is pointed on the screen.

4. If the trigger is pulled (negative going 5 volt pulse that stays low as long as the trigger is held) the game checks to see where the gun is pointed and determines if is a target or not and reacts accordingly.

5. A screen flash is done by the game (usually for one or two frames) whenever the trigger is pulled to make sure the gun can see a spot at that time. If this was not done, you would not be able to shoot dark targets because the gun would not see it.

The counting system for the gun position is such a finicky bastard it's literally a fraction of a fraction of a second. a single frame take 1/60th of a second... one VGA pixel is 1/307,200 of 1/60th of a second...1/60 second is 16.67 milliseconds...math it up.

Title: Re: Using arcade light guns with MAME
Post by: ark_ader on September 01, 2017, 11:16:52 pm

Easier to swap out the insides with IR lightguns.  Then mame away.

Title: Re: Using arcade light guns with MAME
Post by: sgould on September 02, 2017, 02:55:55 pm

Thanks for the answers. I think I will look at getting 2 guns or inserts from ultimarc. I must say what a teriffic answer lilshawn totally explained what the dificulties are.

Title: Re: Using arcade light guns with MAME
Post by: Titchgamer on September 02, 2017, 03:27:12 pm

You could get some aimtrak inards from ultimarc then retro fit them to your existing guns

Title: Re: Using arcade light guns with MAME
Post by: nitrogen_widget on September 02, 2017, 10:23:00 pm

I looked into this but since i got a 27" CRT TV and a 32" CRT TV I decided to pick up a ps2 cheap to mod and some guncon2's off ebay.
I also picked up a cheap wii and have modded that and got some cheap wii zapper "guns".
I may even pick up a ps1 and some dual mode guns for the games not on the PS2 or wii.

I will be using those for my shooter games because honestly it was cheaper than two aimtraks and way easier.