Decided to build my own PDA - from "scratch"

Discussion in 'General Smartphone/Handheld/Wearable Discussion' started by Konrad Pierce, Sep 14, 2007.

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  1. Konrad Pierce

    Konrad Pierce Village Idiot 2.0

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    Desperation hits ... asking the Toradex people for specs on their "evaluation board". Without video I can't do anything.
     
  2. Konrad Pierce

    Konrad Pierce Village Idiot 2.0

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    I think I've found the perfect LCD.

    AU Optronics G065VN01 6.5" VGA - exceptional brightness, contrast, response time. Only $65 each if I buy 2 units.

    I'd need to get the digitizer(s) separately though. Not really a bad thing, I would just prefer to get a single-piece LCM ... less chance of things going wrong. :rolleyes:

    [Edit]
    What about a PDA that just folds open to *two* screens? Remove all front-panel buttons completely; dedicate one screen primarily to touch-input, handwriting, or keyboard functions? Perhaps something like the Nintendo DS thing, complete with little "shoulder" buttons on the top corners?

    If I have to buy two screens anyways, I might as well make the best of it.
     
  3. Wail

    Wail Member

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    Mother Of God .. YES .. a PDA with 2 screens is twice as sexy as a PDA with one screen.
     
  4. Inner Prop

    Inner Prop Mobile Deity

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    I second that opinion. It would allow you a larger keypad for an on-screen keypad and a larger screen for viewing text as you type.

    One of the primary reasons I have a PDA is for writing and the biggest wish I have is a bigger screen. My first PDA was a T5 and I have a TX now. Even with those screens they are really too small. I can't imagine how hard it would be with a smaller screen.

    The only bad thing about a split screen is that it doesn't really add to viewing space if you are watching videos.

    I imagine you could arrange it so that you could read text like a book with facing pages.
     
  5. Konrad Pierce

    Konrad Pierce Village Idiot 2.0

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    I've just ordered the screens. Because I still haven't received any of the (promised) support from Toradex, I've also ordered a Triton PXA320 board at the same vendor. I'm not planning on abandoning this project, but I might have to abandon my first choice in processor board. Either way, one of these two boards gets shipped back.

    I admit I briefly entertained the perverted idea of having a two-screen/two-motherboard PDA ... like two independent PDAs that just share a common bus for hardware slots and all. No problems with multitasking that baby ... could even "network" the two together with two different OS platforms, or "double" my wifi connection speeds, or ... the possibilities are endlessly doubled.

    Not this time, though. I still haven't gotten one to work yet ... and it's starting to blow my initial budget expectations - without me yet having procured a case or other (possibly expensive) components.
     
  6. RickAgresta

    RickAgresta General Peanut, leader of the Peanutty Forces

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    Konrad, I don't know the dimensions, but I just saw a cheap clamshell device, picture below. They are all over the drugstores here in the US, don't know about your neck of the woods. Might not be large enough, but thought I'd pass it along. do you still want negative rep, btw? :D
     

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  7. Konrad Pierce

    Konrad Pierce Village Idiot 2.0

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    Hmmm. Cheapo PDA thingies ... I hadn't even considered that option. There's all kinds of cheapo calculators and junk with good plastic in them! Time to head off to Wal-Mart and London Drugs.

    Adama suggested I might look at some of those "dummy" units, like the ones on display at cellular kiosks. I've asked around half-assedly, but nobody seems to have any that I'd like ... apparently they disappear fast, people like to give them to their kids and stuff.

    Latest progress report:
    I have two processor boards (Triton hasn't arrived yet), two screens, 8 batteries, tons of slots and ports and connectors (SD/SDHC, CF, MS, USB, and PCMCIA/CardBus, Ethernet, RS232, BT antennae, many others), speakers and audio jacks, miles of ribbons and cables and wires, plastic bits, resistors and capacitors and all the rest. Many, many LEDS.
    No digitizers (haven't found the "right" ones yet). No case (can't find anything).

    Can't get the Colibri to turn on. :(
    I now understand that the Colibri wasn't designed to function as a "stand-alone" board - Toradex expects you to purchase one of their motherboards to plug it into. They are (so far) unwilling to send me any detailed specs, schematics, part lists, or info about any of these boards unless/until I actually purchase one.

    I am currently modifying my homemade PCI-slot PROM burner to accomodate the pinout of the Colibri's ROM chip. I have already extracted the "Windows CE Core 5.0" ROM chip from the Colibri board so I can 1) copy it, then 2) install the hardware drivers/software I need onto a "virtual" WinCE 5.0 machine, then 3) burn it all as firmware onto another ROM chip - hopefully all operational with my "installed" hardware when I plug it into the Colibri.

    ---

    Oh yeah, RA ... more Red Rep is always welcome. I'm trying to drag my good name down into the mud, y'know ... been handing Rep out like candy myself and 42 is a long ways off. Would you like me to call you names?

    <Konrad idly wonders in pseudo-third-person that this thread amazingly hasn't drowned off-topic yet.>
     
  8. bigbop

    bigbop Mobile Consultant

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    You should look at the older PALM I, III and other PDAs. They had very large digitizers but you don't realize it because of the escutcheon under the screen that defines the text input areas. A digitizer from an original Palm Pilot is larger than most modern screens and they are standard 4 wire resistive units and you can solder to the pins on the flex cable.

    There are also some toys out there with resistive touchscreens that are quite large. You might also get a case for your project from one of these toys.

    One thing you might look at is the older 3com Audrey http://www.3rdmoon.com/crusso/audrey. They used a 6" LCD touchscreen. I picked one up locally for $5 to play with.
     
  9. NamelessPlayer

    NamelessPlayer Mobile Deity

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    I have an idea-why not try to implement a Wacom active digitizer, like what a lot of Tablet PCs have?

    The upside is that it's generally more precise than a resistive touchscreen, and also offers pressure sensitivity.

    The downside? You need a special stylus to use such a digitizer.

    Of course, there's passive+active touchscreens out there(see Lenovo X60t/X61t for a few examples), but they're generally quite large.

    I wonder if it's possible to get a passive+active digitizer on a 4"-6" screen...the OQO UMPCs have active ones, but I don't think they have passive capability that lets you use anything else to touch the screen. (But at least that tells us that the small size shouldn't get in the way of the use of an active digitizer.)
     
  10. Konrad Pierce

    Konrad Pierce Village Idiot 2.0

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    Thanx bigbop, Nameless ... good suggestions.

    Your recommendations are great. I looked at the Audrey thing, and some info about Wacom. I'm actually all confused now. The vendor that sold me the screens also sells digitizers ... 4- and 5-wire Resistive, Capacitive, Surface Acoustic Wave, Infrared ... active, passive ... I don't know a thing about this stuff. I naively assumed that (as far as LCD touchscreens go) a digitizer is a digitizer, some better than others, but all the same stuff. I'm also looking around a site that somebody recommended - here.

    I've also learned that any kind of LCD and/or digitizer can easily be "cut down" to the needed dimensions and resolution. Basically at the factory - I don't happen to own all that fancy precision machinery - and the cost is slightly greater than the piece(s) being cut down. So I'm not too concerned about the dimensions, as I can order special-cut custom-sized digitizers if I absolutely have to.

    Are you nuts? Aren't these older Palm devices all notorious for having cheap low-quality problem-prone digitizers? :p

    Besides, my screens are 6.5" (132.48x99.36mm active diagonal). After looking around extensively, I chose these because they
    1. Have the best overall resolution (640x480x18-bit, 0.069x.207mm pitch) I could find in a screen measuring around 6"
    2. Have excellent brightness (500cd/m², >80% uniformity), contrast (>450:1), and response time (<26ms); good viewing angles (70-70-60-60°), low power consumption (3.84-4.5W, 3.8-5.0mA @ 3.3V), Anti-glare surfacing, 3H hardness treatment, exceptional operating tolerances (most importantly: high impact/shock resistance)
    3. Have comprehensive technical data available
    4. Are (surprisingly) priced similarly to all the other (clearly inferior ;) ) screens
     
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