Posted by Reg on 31, 2001 at 10:33 PM:
Hi,
Here are the results of my tests with a NES Light Gun
tested with an an oscilloscope:
P.s I'am new to use an Oscilloscope...
1. If you cut the wire of a Nes gun you will see the
following wires (White "+5V", Brown "Ground",
Blue "Gun out", Purple "Gun trigger").
2. To give power to the NES gun and few electronics,
you need to hool up the gun to these Joystick pins
(Pin 1 "+5V", Pin 4 "ground for button 1")
3. The Gun have been tested with a regular 27 inch
Color TV.
4. The Gun can see a white spot small as a "Dime"
at 4 feets (may be less than a dime like the size
of a pen eraser "the ones made of woods").
5. The Blue wire of the gun have the following signal
(if the gun is pointed to a white picture:
/| /|
/ | / | +30 mili volts
-----/ | -------------/ | --- ...
| / | /
| / | / -30 mili volts
|/ |/
| | ----> 1 micro seconds approximatively
| | ----> 18 micro secondsI have overlapped a 60 herts signal over it and it
and the signal is also 18 micro seconds.
6. I have amplified the signal with two PNP 2N3906
and the signal have now this shape:-----| |---------------| |-- ...
| | | |
| | | | .5 volts
|______| |______|
| | ----> 1 micro seconds approximatively
| | ----> 18 micro seconds
7. The idea is to trigger the Switch 4 of the
Joystick 1 homemame circuit that I have created do
the following:amplifiy the signal of the gun, clean it and
trig the switch4 of joystick 1,
will be distributed soon...)8. Why joystick 1 and switch 4, see below
(previous post)
First here is a list of games that support Guns:
Night Stocker (nstocker) Bally/SenteCheyenne V.1.0 (cheyenne) Exidy
Chiller V.3.0 (chiller) Exidy
Clay Pigeon V.2.0 (Claypign) Exidy
Combat V.3.0 (combat) Exidy
Crack Shoot V.2.0 (cracksht) Exidy
CrossBow V.2.0 (crossbow) Exidy
Hit'n miss V.3.0 (hitnmiss) Exidy
Hit'n Miss V.2.0 (hitnmis2) Exidy
Showdown V.3.0 (showdown) Exidy
Who Dunit V.8.0 (whodunit) ExidyTerminator2 JudgmentDay (term2) Midway
PChoice-10:Duck Hunt (pc_duckh) Nintendo
PChoice-10:Hogan's Alley(pc_hglaly) Nintendo
PChoice-10: Wild Gunmen (pc_wgnmn) NintendoTurkey Shoot (tshoot) Williams
I have seen most pictures of these cabinets and
most of them have their gun fixed on the cabinet.
That mean that to move the crosspointer on a target,
the gun is acting like a big joystick...For the trigger Mame already support the Joystick
button 1 of Player 1,so clicking this button is the
same as using the trigger of the gun.The optics are emulated but not ready to be used as
is, in Mame without modifying the drivers (like
Exidy440.c) by example...But If someone buy at Ebay a T2 gun by example Mame
will support it if we hack it with a old joystick for
the crosshair positionning and use the button 1 of the
joystick for the gun trigger...Mame will work great without the optics...
Just try a regular joystick to play T2 ot Clay Pigeon
and you will see...If we really want the optics to be implemented, we
must amplify the output of a Nes Light gun to trigger
a relay like the one implemented in a CMOS 4066 and
then trigger button 4 of player 1 of joystick port...Why Button 4, because buttons 1,2,3 are used by the
games list previously...
A light gun is sensing light all the time...when the trigger is activated it send a signal to the
PC to reset their counter and to display a black frame
with a small white cursor that moves, when the gun
see the cursor it send a signal to the PC to stop the
counter and this way the computer know by calculation
where the gun was pointed...So button 4 can be use to tell the computer to
determine if there was a miss or a hit...by modifying the Exidy driver most guns games in Mame
will work ..and apply the same process for Midway, Nintendo and
Williams...
9. In conclusion, I think the gun can be attached
on a homemade base for most games...
be detached for games like may be
Duck Hunt of PChoice-10.10. Exidy already implement most of the process to
make the optics of a light Gun to work..Some modifications to the Exidy driver need to
be done to recognize the switch 4 of Joystick 1
so Mame can know when the gun see a white cursor.Some calculations are already implemented...
in the Exidy driver...some work need to be done
to match the real gun and the emulated one...bye
Reg