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 Post subject: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 2:01 pm 
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I have a technical question about the NES zapper gun.

I've been told that zapper games don't work with flatscreen TVs. I would assume that would be related to lag in display (?). Presumably, the game would be polling the zapper before the correct frame was displayed.

If you sent the 'black screen with white squares' to the PPU to display... then waited 3-4 frames before polling the zapper...would you be able to make flatscreens work with the zapper ?

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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 2:15 pm 
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No.

The zapper is only sensitive to the ~15kHz flicker of CRT TVs. Flatscreen TVs usually don't flicker close enough to that frequency to trigger the zapper.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 2:25 pm 
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Perhaps if a TV flickered its LED backlight with 15.7 kHz PWM, a specially designed game might be able to work. But it wouldn't necessarily be able to do the more subtle tricks that games like Operation Wolf use. It measures the time between the start of the picture and start of receiving light to narrow down targets. And Zapper users are a far smaller market than Wii Remote users, probably not near big enough for economies of scale.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 2:42 pm 
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Just to play devil's advocate here...

I've been able to get a false positive by pointing a zapper at a fluorescent bulb and shooting. Are you sure the flicker is necessary?

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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 2:49 pm 
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Your compact fluorescent lamp's electronic ballast might be operating at a frequency close enough to 16 kHz for the Zapper to pick it up.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 3:11 pm 
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It depends entirely on how bright the light source is.

I have been able to get the zapper to fire with a single LED driven with 10mA, turned on once (no repetition at all). But I also can't get it to fire pointing at the CCFLs in my monitors or the CFLs in my house, even though I know the former is flickering at ≈1kHz and the latter at ≈8kHz.

The receiver inside the LCD is basically equivalent to the GL3274, but retuned for 16kHz operation instead of 40kHz operation. You can look at the rejection plot in its datasheet.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 3:21 pm 
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If you want to test your TV I made some test ROMs a while back, and there's also tepples' zapruder suite.

viewtopic.php?f=9&t=13021

The issue isn't just lag, though, like others have pointed out.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 4:18 pm 
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I guess the market for zapper games is too small for me to work on this issue. It's a bit disappointing.

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 Post subject: Re: NES zapper + LCD
PostPosted: Sat Aug 06, 2016 5:48 pm 
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A while back I started disassembling Duck Hunt, figuring I could add latency to make it work, but then I learned the zapper just can't see my TV anyway, so I gave up.

I was happy about the idea of a software solution to the problem, but when I realized people would have to mod their zappers too to make it work, I wasn't so interested anymore. You'd need both, though, to get it going; software to adapt for latency, and hardware to detect the light.


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 Post subject: Re: NES zapper + LCD
PostPosted: Sun Aug 07, 2016 3:45 am 
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Wouldn't four black/white frames look absolutely awful? Epilepsy trigger?


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 Post subject: Re: NES zapper + LCD
PostPosted: Sun Aug 07, 2016 5:29 am 
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Maybe the lawsuits related to "epilepsy trigger" are why there wasn't a light gun for the Nintendo 64 or GameCube, despite GunCon for the PlayStation and PlayStation 2.

In my opinion, going forward, the Anoto watermark and the Wii Remote appear to be the most promising technologies for pointing at an LCD once their patents run out.


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 Post subject: Re: NES zapper + LCD
PostPosted: Thu Sep 01, 2016 10:21 am 
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Anyone here see this? https://www.youtube.com/watch?v=DzIPGpKo3Ag


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 Post subject: Re: NES zapper + LCD
PostPosted: Thu Sep 01, 2016 12:59 pm 
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Yes...

viewtopic.php?f=9&t=14760

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 Post subject: Re: NES zapper + LCD
PostPosted: Wed Sep 07, 2016 8:58 am 
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rainwarrior wrote:
I was happy about the idea of a software solution to the problem, but when I realized people would have to mod their zappers too to make it work, I wasn't so interested anymore. You'd need both, though, to get it going; software to adapt for latency, and hardware to detect the light.

It's not a bad idea. On the software side, it would be best to make the delay adjustable (to account for various TV sets); but then the lingering problem of hardware modification crops up. I think there's a definite interest, as I've seen tons of YouTube videos of people talking about why Zappers don't work (usually with varying degrees of accuracy), but never underestimate how many people would go through the pain just to shoot those beautiful Nintendo ducks. :)

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