NES zapper + LCD

Discuss technical or other issues relating to programming the Nintendo Entertainment System, Famicom, or compatible systems.

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Punch
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Re: NES zapper + LCD

Post by Punch » Fri Sep 21, 2018 4:23 pm

This is big, why is this thread so low key? Imagine the homebrews... If this really works then lightgun games can finally get out of the "I own a heavy obsolete display" domain.
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lidnariq
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Re: NES zapper + LCD

Post by lidnariq » Fri Sep 21, 2018 4:31 pm

Because it doesn't?

This only works because his lightgun works entirely differently than the OEM Zapper.

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rainwarrior
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Re: NES zapper + LCD

Post by rainwarrior » Fri Sep 21, 2018 4:38 pm

Well, it was news to me that some clone light guns don't have the filter. That puts a new lease on the idea, I think.

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Punch
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Re: NES zapper + LCD

Post by Punch » Fri Sep 21, 2018 7:44 pm

lidnariq wrote:Because it doesn't?

This only works because his lightgun works entirely differently than the OEM Zapper.
?????

So what? A cheap circuit like that is miles better than wiring a duct taped wiimote/zapper combo to a raspberry pi. Can you seriously not see how viable this is if a cheapo clone can simply work with LCDs just by adjusting for lag?

I for one have been waiting for a viable LCD solution for a long time for homebrew games...
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lidnariq
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Re: NES zapper + LCD

Post by lidnariq » Fri Sep 21, 2018 7:52 pm

Because now you're in the business of manufacturing, or finding someone who is still manufacturing, new famiclone zappers with a compatible connector?

And you have to explicitly say "your existing Zapper won't work, you'll have to buy a new one" ?

I mean, I agree that it's not nothing. But it's also a lot of caveats, which is why I'm so "low key" about it.

You're seeing this in comparison to a camera and a computer or to a CRT. I'm seeing this more like trying to sell an entirely brand new peripheral, even though it seems like one that's already been sold.

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rainwarrior
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Re: NES zapper + LCD

Post by rainwarrior » Fri Sep 21, 2018 8:37 pm

lidnariq wrote:Because now you're in the business of manufacturing, or finding someone who is still manufacturing, new famiclone zappers with a compatible connector?
Hyperkin is selling this one for NES. Couldn't find a currently made clone for Famicom though (but I might not know how to search for it).

I will get one to try, if it has the CRT filter I'll try modding it, and if I'm very lucky it won't.

I wasn't really willing to mod my original zapper but I'd at least be willing to do it to a cheap clone like this.

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morskoyzmey
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Re: NES zapper + LCD

Post by morskoyzmey » Sat Sep 22, 2018 3:02 pm

rainwarrior wrote:
lidnariq wrote:Because now you're in the business of manufacturing, or finding someone who is still manufacturing, new famiclone zappers with a compatible connector?
Hyperkin is selling this one for NES. Couldn't find a currently made clone for Famicom though (but I might not know how to search for it).

I will get one to try, if it has the CRT filter I'll try modding it, and if I'm very lucky it won't.

I wasn't really willing to mod my original zapper but I'd at least be willing to do it to a cheap clone like this.
Moreover I have positive report about this gun: https://twitter.com/rookytooky/status/1 ... 3367101440

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Re: NES zapper + LCD

Post by darkhog » Thu Sep 27, 2018 5:32 am

Original zapper may not be possible to get working with LCDs, but how about specially designed one that's basically a simple digital camera detecting patterns made by zapper-controlled games (black frame white frame black frame) and sending appropriate signals back to console (hit/not hit, etc.). Output of the CCD would need to be put through some hi/lowpass filter so values over certain luminosity are considered white. Anyone with appropriate electronics knowledge that could do it?

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Re: NES zapper + LCD

Post by tepples » Thu Sep 27, 2018 8:18 am

Even if it's changed to respond to all light (not just SDTV scanline frequency), and even if games are reengineered to accommodate scaler lag, it still wouldn't work for games that read up or down by timing from the top of the screen to when light is first seen, such as Operation Wolf. Nor would it work for Super Scope games on Super NES, which read not only up and down but also left and right at a 2.7 MHz (2 horizontal pixel) resolution. The Wii Remote hack would work for both cases.

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Re: NES zapper + LCD

Post by lidnariq » Thu Sep 27, 2018 9:30 am

darkhog wrote:a simple digital camera detecting patterns made by zapper-controlled games (black frame white frame black frame) and sending appropriate signals back to console (hit/not hit, etc.).
Once you have a camera, you need a computer. Once you have a camera and a computer, the Wiimote or "computer vision finds the screen and calculates coordinates from that" designs are simpler, more robust, and don't require patching the game.

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Re: NES zapper + LCD

Post by rainwarrior » Fri Sep 28, 2018 12:17 pm

The Tomee Zapp Gun I ordered from Hyperkin just arrived... and it does detect my LCD screen!

It seems to work reasonably well with morskoyzmey's Duck Hunt beta. In 2-duck mode, sometimes it gets the wrong duck, but I think that's something that could probably be fixed with better delay calibration.

1. Detects light for about 1/2 a second before the signal stops. (i.e. if you point it at an unchanging white spot on the screen, it will give signal for 1/2 a second.) I'm guessing it tries to automatically adapt to the brightness of the room with a slow filter. (Doesn't seem to be a problem for quickly changing light condition like in duck hunt.)

2. Trigger (D4) seems to always report 1 when open, and 0 when pulled. (The normal NES zapper is 0, then pulling it is 1 for 6 frames or so before it returns to 0.) This is good enough for the way it's used in most games, I think, but it is a pretty notable difference in behaviour.

As a quick guess I'd assume they did this because the reverse (unfiltered always 0, 1 when pulled) was a problem for some common games, but I'd have to do some checking to verify.

So... that's pretty cool. A cheap and readily available zapper clone is capable of reading an LCD screen.

Attached a picture of the disassembled gun, and the tiny circuit on the back of the sensor.
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zapp_gun_package.jpg
zapp_gun_circuit.jpg
Last edited by rainwarrior on Fri Sep 28, 2018 12:48 pm, edited 1 time in total.

lidnariq
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Re: NES zapper + LCD

Post by lidnariq » Fri Sep 28, 2018 12:39 pm

Appears to be the same schematic as I RE'd earlier, just with resistors of twice the size as last time. (1M -> 2M; 100k -> 220k)

The only things I can't tell by visual inspection (for both boards) are
1- how big is the capacitor, and
2- photodiode or phototransistor

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rainwarrior
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Re: NES zapper + LCD

Post by rainwarrior » Fri Sep 28, 2018 12:47 pm

There is a D on the side of the board next to the light sensing component. Would that imply diode?

Edit: I checked it in-circuit with a multimeter diode tester. With ambient light conditions, was giving 1 in either direction. With a flashlight next to it, I got .3 in one direction (positive/red to the right side on the circuit on the back, negative/black to the left i.e. touching that J3Y part.)
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zapp_gun_sensor.jpg

lidnariq
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Re: NES zapper + LCD

Post by lidnariq » Fri Sep 28, 2018 1:22 pm

Sounds like a good guess to me.

Edit: hm, I think those results more nearly imply a phototransistor? photodiodes should look like a diode even when receiving light.

Apparently the marking "J3Y" reliably means the S8050 NPN BJT ? Seems like a pretty typical one, with a current gain of about 200 in the range it's operating in here.

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morskoyzmey
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Re: NES zapper + LCD

Post by morskoyzmey » Sun Sep 30, 2018 1:32 am

I must share this https://twitter.com/eNuffGs/status/1046244128365805570
One guy just swapped Zapps LED (phototransistor or whatever) with one in original gray Zapper and it worked for him.

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