EED2 Project Underway

DigiTan · Posted: 22 Oct 2004 02:54:20 pm Post subject:

This week I'm going to start on an upgraded version of the External Expansion Device (EED).

The first design allowed any calculator to be powered from a wall adapter and also trippled the battery life by adding AA cells. EED2 will go even further and add 512KB of external RAM (~18 times the original RAM size). The external FLASH can store progs, backups, and pretty much any other kind of 8x.* variable. Other new features will focus on...

Smoother Power Switching

If space allows, the battery/wall switching circuits will be upgraded—so the calc will no longer self-reset if you get unplugged unexpectedly. Also, you’ll be able to unplug the calculator from the wall without turning the calculator off first (this was the biggest limitation in the original design).

Better Look

Finally, I’m overhauling the wiring for better aesthetics. This means no more unsightly exposed busses! The circuit board will be custom-etched this time around to take up less space.

Returning features:
• 3 Power supply options (AAA batteries, AA batteries, or Wall Adapter)
• Automatic power switching
• 24 Hours battery life
• Power adapter can handle 7-18 volts
• Side-mounted “external power on” LED
• Tougher 2.5mm link
• 3.5mm port can power snap-on peripherials

New features:
• Serial DataFLASH memory of 512KB
• Store up to 9 files, including backups (expandable to 1 Cool

• 1-key interface
• 2 red/green/orange “mode” LEDs
• Better power filtering
• No more exposed busses!

Possible features:
• High-voltage protection from voltage spikes (need to order new parts)
• IR link support
• Universal Translator (will require lots more reseach)

jvdthwip · Advanced Newbie Joined: 21 Jun 2004 Posts: 93

Sounds awesome... except... Won't there be a lot of programming and modifications required for the calc to use the external device? Will the device require the potential user to look around for all the needed parts and assemble from a cryptic guide? Are you going to patent it and get it professionally assembled? Can it be purchased from an online service if you decide to do so?

Adm.Wiggin · Posted: 23 Oct 2004 05:04:57 pm Post subject:

Dude, do you have ANY idea how much it would cost him to take such an endeavor? It's not exactly a small investment.

You find your favorite electronics store, buy the parts, read the instructions. If it doesn't work, you screwed up.

DigiTan · Posted: 23 Oct 2004 05:06:59 pm Post subject:

Yeah, the mod will most likely have a really long building time (even more so than the Playstation mem card mod. So far the walkthough guide will include all the source code needed to pull it off (materials lists, step-by-step guide, etc). I hoping to do it all under $25 and stick mainly to parts that are much easier to find.

DigiTan · Posted: 03 Nov 2004 01:03:45 am Post subject:

Okay, here's the preliminary layout. To get an idea of how it compared to the first EED, the parts inside the red box represents the original EED system. Pretty much everything else is brand new. I had to throw in a few annoying bridges this time because it was impossible to create the circuitboard without 'em. The orange and yellow boxes show the 512KB Archive and the controller. Anyway, I downloaded a nice CAD program that will probably speed up the project by a few weeks. I'm estimating the project cost at around 35 US$. More updates later...

Arcane Wizard · Posted: 05 Nov 2004 12:59:53 pm Post subject:

DigiTan, how would you feel about becoming a UTI member, getting an ftp account (standard issue : ) ) and getting your own subforum for this project?

DigiTan · Posted: 07 Nov 2004 01:16:15 am Post subject:

I guess the topic is better off here in the mods section, at least until more progress can be made. But thanks for the invite!

[Update] The first circuitboard design is printed out on paper now. Sometime this week, I'll go to Office Max and make a transparency copy for the UV etching. This will put the project well ahead of schedule. The rest will not be so easy. Some of the circuit traces are extremely close together, so there's little room for error. I'll try to make a "ratsnest" prototype out of spare parts this week. We'll see how it goes... Cool

shadowing · Posted: 15 Nov 2004 11:37:41 pm Post subject:

well... all I could say is wow!!! I would really like to try this, but then I have no expertise in circuitry. I could probably ask my dad. Think he could help me understand. well, still... WOW!!!

Sorry for repeating. If there is any way I could help, plz let me know. I think it is a great idea.

DigiTan · Posted: 16 Nov 2004 08:54:48 pm Post subject:

Yeah, it a pretty elabore scheme. Right now, the hardware part is sort of on hold because of 'exam month.' Plus I have to repair the old EED and get the link working again (never use exposed wire). There's also another snag, because of the FLASH chip works, I have transfer calc from the link, then into RAM, and then into FLASH. Hopefully I'll have some simulations done in a few weeks. Cool

TeamoComputers · Newbie Joined: 06 Oct 2004 Posts: 10

Was just wondering about the status of this project..

DigiTan · Posted: 11 Jan 2005 11:35:30 pm Post subject:

Heh heh. Good question. Wink

Well, I downloaded some new info in the TI link protocol, and I'm hoping to write a basic (er...basic ASM) transfer program by February. The prog simulations should show whether the FLASH chip is quick enough for the job.

The latest CAD board layout is done. I just need to make a transparency copy of it at Office Max and do the UV etching.

The whole thing will probably boil down to the etching goes. It was supposed to be easy, but since I didn't fininsh my circuit-etcher project over Christmas, it'll have to be done by hand. That's something I don't have a lot of practice in, and let's just say there's a lot of things that can go wrong. Plus, half my chemicals leaked out in a garage (huge mess), so those will have to be replaced.

But other than that, things are looking up. The design is 100% done. The componets are here. The equipment is..for the most part, ready. It's just a matter of finding the time.

DigiTan · Posted: 07 Mar 2005 04:55:44 pm Post subject:

Okay. I know this project is looking pretty dead now, so I'm going to work on it over spring break, starting today. I'm hoping to finish a flimsy prototype before next monday and hopefully have a (real) circuit board done a week after that.

Also, I might build a tilt-sensitive Calc Guardian attachment to ward of possible theives.

Adm.Wiggin · Posted: 18 Apr 2005 04:49:54 pm Post subject:

Hate to pry, but how's it coming, DigiTan? Any luck? I'm really interested in Eed2...

DigiTan · Posted: 01 Jun 2005 01:40:54 am Post subject:

This might be one of those cured projects. The hardware is designed but I still have to port the software from C to ASM so I get this flash chip to work. I also got a bit distracted redisigning the original EED (no more horrendous exposed wires). I finally moved out of school today so hopefully, I'll get to start on this flash code.

Solitaire710 · Advanced Newbie Joined: 14 Mar 2005 Posts: 55

*Really, Really, Really Interested*

aforsy · Posted: 04 Jun 2005 11:30:30 am Post subject:

hey, this looks really neat! you might even want to think about patenting and marketing it like jvdthwip said! sure it costs money to start with, but if you're willing to make the investment, the payoff could be substantial!

i, for one, would certainly buy it (or actually probably get my parents to get it for me for my birthday :biggrin: )

elfprince13 · Posted: 04 Jun 2005 03:27:08 pm Post subject:

I bought my calc myself...hoping to buy a laptop (or Mac mini) myself...would buy this too

aforsy · Posted: 07 Jun 2005 07:15:14 pm Post subject:

yeah, i wish i had money...i get twenty dollars for mowing the yard, but it doesn't really add up too fast...i guess i ought to get a job...what a pathetic loser i am, heh.

elfprince13 · Posted: 08 Jun 2005 08:48:48 am Post subject:

elderly relatives who want the house painted are nice...Im drifting off topic....back again.....you definitely need to finish this project...you could start a mail order business

Adm.Wiggin · Posted: 08 Jun 2005 10:03:27 pm Post subject:

If/When he finishes it, I'm sure he will provide detailed instructions for you to "build it yourself".

It's up to him whether we would make you one for a small fee (think large DigiTan, he looks like he *really* wants it Laughing

)

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