So, I ordered some parts for the LCD board tonight. Here's my anticipated design:

• 4-Wire drive- most LCDs need at least 7 wires for control.
• Input- four small push buttons
• LED output- four small LEDs
• Backlight control- both for LED backlighting and EL backlighting
• Encoder input- knob to turn for input control, backlight dimming, or whatever.

The end goal is to provide a smart LCD that the user can write to and read from with minimal fuss- two bytes of command (say, address and contents) to place a character anywhere on the screen. No waiting for the display to update- the on-board micro will have a map of the screen contents and check for characters that need to be changed every 100 ms or so. LEDs can be turned on or off, maybe a few other fun things. We'll see how it plays out.

Other items I'm going to work on this week:
Magic square wave generator- an 8-pin IC that generates square waves up to a couple hundred kHz, with variable duty cycle, all set by grounding pins or connecting resistor dividers to them. Much easier than figuring out values for 555 timers. I need this for my laser-gun project.
Encoder decoder- translates the quadrature output from an encoder to pulse/direction or pulse/pulse. Actually, I already made this, for free-turning steering wheels to go on a buddy's MAME cabinet (Ironman Ivan Stewart's Super Off-road FTW!).
Remote mini-joystick control panel for the Arduino- not necessary for the laser-gun project, but it might make it more fun if a second user can move the target around. I bought some teeny little joysticks from Mouser- should be really cool!

more on the laser gun?

I like lasers!

The idea is simple- I take my old Nintendo Zapper (that I've had since I was 8), a laser pointer, and a couple of motors, and create a meatspace target shooting game.

I'm giving some thought to other stuff I can shoot with my Zapper- one of the more interesting ideas I have is to put a light transmitter on an el cheapo RC helicopter or airplane and use the gun to shoot at it. If I hack the remote, I could even have a successful hit interrupt the controls for 1 second or cut the throttle completely or some such thing.

But baby steps- first the motor game. I have some hope that it'll be ready by next Wednesday's meeting, but that may be foolish optimism, as I ordered the parts last night on 2nd day delivery which almost certainly means I won't have them until Tuesday, and although I'll frontload as much work as possible, not putting it together until Tuesday night is a poor recipe for success.

like laser tag?

with actual lasers?

Sort of like laser tag. In laser tag, you shoot your opponent. In my game(s) (as well as the original Duck Hunt/Nintendo Zapper games) the target shoots EVERYONE and your gun sorts out whether you're close enough to on target for it to matter.

Let's consider the RC helicopter model. The active target method involves putting a modulated omnidirectional light source on the helicopter (say, 4 LEDs with fairly wide half-angles) and then looking for that light when you pull the trigger on the gun. The Zapper has some nice built in baffling and lensing, so it excludes light which diverges from its aim point quite well. Should the Zapper register a "hit" (i.e., pick up enough of the modulated light)(it knows you hit the target because the target is flashing at 15kHz[NTSC screen refresh rate] and very little other light in the room is), it would be connected by some logic to the remote control which would then stop sending control signals for a brief period. The modulation could be done by my magic square wave IC; if I used surface mount parts, I could put the light source together with a fairly minuscule mass.

Now let's consider the passive target method. I get a light source (laser pointer, or LED with some collimating lenses and baffles to make it more beam-like), modulate it (for ambient light rejection) and point it at the mini-chopper. On the helicopter, I need several pick-ups, a demodulator, and an IC which can detect a hit and shut down the helicopter. It's a little more complex, but not too much so- the worst part would be the demodulation hardware. I'd guess that the mass required would be 1.5 to 2 times as much as for the active target method.

For laser tag with people, the equation is different. I'm shooting at you, and your system should shut down when you get hit a certain number of times. If we did an active target model, you'd transmit, I'd receive, then I'd have to transmit BACK to you that you got hit. Complexity goes up fast.

or even easier, you take a rc helicopter that already has the ability to be "shot down" and modify the gun to only produce a very narrow beam, like a laser