Here at Bingy U, CS210 is Machine Org 1. So far it's been theory on logic gates, truth tables, adders, etc. I expected our electronics kit (which we haven't received yet) to just be gates, but apparently we'll also get some microchips (Atmel something or other, I think) with ram and flash rom, which we'll get to program in C.

And please do make an electronics forum! I don't know much on the topic, but I'd love to start learning!!!

KERM! Your constituents compel you to make the subforum!

I'll get on it. In the meantime, some very random and assorted thoughts on my work thus far.

1) I was going to jam AAAA (not a typo) batteries into the pen, but there's no way that 3v is going to cut it. Therefore, I am making this pen PS/2 for calculators, specifically, and mooching 5.1v off the PS/2 port. Needless to say, this requires a TICI Hub or an UltCalc-type internal modification.

2) Optics are problematic, specifically isolating LED and photodiode. Need to find me some light pipes, just thought of some old hardware to strip pipes out of while I was typing this.

3) The circuit looks like it will work, just need to tweak calibration for 0/5v output.

4) Software is pretty straightforward; I'll write a DCS driver for this as soon as I have the full optics in the pen and the circuit on a breadboard. Then, once software is functional, I'll assemble the circuit into the pen so it's just a pen with a PS/2 tether.

Taking apart 9v batteries are we? And I took a look at your Ultimate Calculator(s) (so much for the RE/BE ); pretty good work , but you need to work on your spraypainting skills (have you tried using vinyl dye to paint your plastics?)

And if you don't mind mentioning that I came up with part of the idea, when you've posted the awesomeness for the world to see, I'd be really really happy!

Of course I will mention that. Credit where credit is due, good sir.

you could stack 4 of those laser-pointer sized button batteries. I think that's 6 volts.

This is true, but I still like the elegance of the PS/2 solution for now. Working on putting some fiber on an infrared LED to see how that works.

Sigh...an elegant solution that I would have to build extra hardware to duplicate Still, it'll be fun!

Here's the preliminary physical schematic. The button, support, and light sensor are in place; need to jack a light pipe, thread the optical fibers around the body of the pen, and then it's circuit refinement and software time.

Looks pretty cramped in there; how big is the pen?

It's tapered, about 1/2" OD near the back and 1/4" OD near the tip, which makes it maybe .4" ID at the back and .2" ID at the front. I have been able to fit everything in so far without trouble, as long as I put the LED behind the switch. I chose not to show the tapering of the pen in the diagram to keep things simple.

ooooo, nice work Kerm.

Its a good thing you labeled the pen clip. Don't want anyone getting all worried that they wouldn't be able to clip it to their pocket protector

Always the critic, aren't we? Just need to figure out if this IR LED is actually sufficient to trigger the photodiode, then I can mount it and its fiber into the chassis.

Wow. In a couple days, you've already almost-halfway implemented this idea! Now that's what I call service.

Seriously, though, I agree with the idea posted a while back about scanning in 8x8 blocks. Not only would it almost sufficiently fast for practical use, but the trade off of a loss of precision would be somewhat negligible for the purposes of a light gun style game. Actually, for a light gun game, you wouldn't even need to do that. You would just darken each target one at a time in quick succession (like duck hunt actually does, assuming my eyes aren't lying to me looking at something going that fast).

Hmm... So many possibilities... Now that I think about it, the pixel precise version could also be useful for a drawing application (line drawing only, though, because of the tap-to-detect nature of the pen -- i.e., you would only be able to tap in different places to connect lines from point to point).

I guess it's all possible depending on what you do in software. I certainly look forward to seeing the results.

Ooh, ooh, afterthought! I wonder if you could obtain sufficient power from the USB-OTG port of the 84+? I like to cling to my belief that USB stuff is far more accessible than stuff requiring a TICI hub (I do know someone who actually built one, though), although I do understand your affinity for... well, stuff you invented. If this turns out to be something I can build myself, I will probably try a USB version out. USB-OTG supplies up to 100mA, +5V, I think.

Yeah, I'm going to have to start posting my crazy ideas here more often, since it seems like stuff actually gets done here! Also, I thought of drawing power from USB, but that would mean having two connections (USB and serial link) since USB devices are much more complicated to design and build than serial devices (am I right?) Plus, it would leave 83+ers out in the cold, whereas this solution can work for them too, if they build a hub.

Sadly, seeing at how complicated the pen looks to me, I probably won't build one myself any time soon, but I can't wait to see some videos of it in action, and look at whatever source code Kerm comes up with to interface with it!

Here's two pix of my random hardware mutterings for your perusal:


L to R: Photodiode, plastic support, button. Bottom: IR LED with fiber bundle


Batteries, LED /fiber /button /support /photodiode construction, pen casing w/o rubber grip

Still waiting on my blue diamond

Another pix for you guys, heading out for the evening.


Test board with circuit, pen with button, light sensor, light pipe to tip. Clicking works.