Controlling 3D glasses with an Atari 2600

[Pioneer4x4]

Another project I had was controlling 3D glasses with an Atari 2600. I have working code but not sure which version was the one that actually worked, I need to test it on hardware. Basically some glasses (I started with the old crappy/tiny viewport) Sega 3D glasses, then I got a pair that came bundled with some video card or something. Let me 'splain, no, there is too much, let me sum up...

The glasses have a mini 1/8" stereo jack on them with a common pin, and one pin for each LCD shutter. If I recall, you just apply 5v to a pin and ground the common, and that shutter goes dark. So to display 3D;

Send power to 1 shutter, blocking that eye from seeing the screen.

Display the image on the screen that the other eye should see.

Remove power from 1st shutter, and apply to the other.

Display the other image.

 

I sent data out to the joystick port to turn pins on and off, and that actually controlled the 3D glasses directly. If I remember, no electrical components were used, only a wiring adapter from 9pin D-Sub to headphone jack.

 

I can't even remember how exactly it worked in code, but this is one piece I found on my old HD.

 

set romsize 4k

set tv ntsc

set smartbranching on

dim frame = a

dim rate=b

rate=0

COLUPF = $06

main

rightframe

rem frame 1

frame=1

playfield:

................................

........X.......X...............

........X.......X...............

........X.......X...............

........X.......X...............

........X.......X...............

........X.......X...............

........X.......X...............

................................

................................

................................

end

for c=0 to rate

drawscreen

next c

leftframe

rem frame 2

frame=2

playfield:

................................

.....X.......X..................

.....X.......X..................

.....X.......X..................

.....X.......X..................

.....X.......X..................

.....X.......X..................

.....X.......X..................

................................

................................

................................

end

for c=0 to rate

drawscreen

next c

goto main

vblank

SWCHA=frame

SWACNT=%00000011

return