Connect with us

Cellphone LCDs (color) - again

Discussion in 'Electronic Components' started by Lewin A.R.W. Edwards, Nov 2, 2003.

Scroll to continue with content
  1. Hi all,

    I asked here about small LCDs with COG controllers recently, and had some
    interesting suggestions, but nothing that directly led me to being able to
    prototype my project. After investigating the matter a lot deeper, it seems
    like my only option is to repurpose a cellphone display. I'm aware of
    numerous projects that involve monochrome LCMs from different phones. But I
    need one grayscale LCD and one color LCD. I need at least 4 grays,
    preferably 8. Not only are all the projects I can find monochrome, but most
    of them use European phones, and it's quite difficult to cross-reference the
    numbers with equivalent U.S. models.

    I don't mind spending a couple of hundred dollars on these displays if need
    be - so it's quite acceptable for me to have to buy and junk a brand-new
    cellphone. But I need to be *sure* that I can use the LCD.

    Can anyone point me to a homebrew project that will lead me to suitable
    cellphone LCDs available in North America? To reiterate my needs:

    1 grayscale STN LCD ~1" diag or smaller, 96x64 or so is fine (anything down
    to about 48x48 is probably OK). Minimum 4 gray levels.

    1 CSTN LCD, at least 2 bits per color component, ~1" diag or smaller, same
    kind of resolution requirement as above. This is more important than the
    grayscale one, actually.

    LCD must have integrated controller. Anything much bigger than about 1.5"
    diagonal is too large.

    I've found numerous parts that would suit me fine, but they're just not
    available as samples. I've also found plenty of sites selling replacement
    LCDs for cellphones, but no datasheets for those parts. So I'm kind of
    between a rock and a hard place.
  2. Lewin, there are several local companies that rebuild cell phones,
    and at least one wholesaler who sells the replacement displays for
    pagers and cell phones.

    I think it is:
    Crystal Exchange Inc.
    7365 Southwest 38th Street, Ocala, FL 34474
    (352) 291-1222

    I can call them tuesday, and verify it for you, if you want me to. I
    have to spend Monday driving to and from the Gainsville VA hospital, so
    I won't have much free time on Monday.

    4551 Northwest 44th Avenue, Ocala, FL 34482
    (352) 671-6707

    This is the company that does wholesale pager and cell phone repairs. is a list of some other
    companies that deal with cell phone repairs, etc.
  3. Hi Michael,
    Great, the question being - do they have data on the LCDs? :) There's no
    problem finding people who sell LCDs, but you simply tell them a cellphone
    model and they ship you an LCD in a box. I need to know that the LCD in
    question has an integral controller, and what chip it is, so I can get the
    datasheet and have a hope of programming the thing.

    (The reason it needs to have an on-chip controller is because I'm
    controlling it from an 8-bit MCU without LCD controller).

  4. I'll try to find out, next week. From what I understand, they have
    service data on the phones, and I think I still know someone who works
    there. I was offered a job there last year but I can't handle mandatory
    overtime, so I had to turn it down
  5. If by complete COG you mean the display with the scanning controller,
    I don't think you will be able to find it. Don't take my word for that
    though. As for gray levels in passive displays, I have learned this
    trick is performed by a kind of time based modulation on pixels
    similar to PWM in wich one keeps the pixel on a number of scans out of
    16. Same with colour passives. So I don't think it's pratical having
    more than 4bpp for passives.

    Have you considered a CPLD to performe this video function? I had to
    build one for a Z180 based legacy design and it took me longer to
    learn VHDL than to implement the design itself though only 1 bit per
    pixel. I don't think extending to 4bpp. As long as you know VHDL, it
    won't take too long to have the thing running.


  6. Hi,
    I think you're wrong on this. The monochrome LCDs certainly have integral
    scanning controller. In some cases they even use a serial interface
    (Ericsson LX588, LX788, related GSM models, etc).

    For experiment's sake I opened my Nokia 3595 (96x64 color, pretty much
    exactly the device I want) and scoped the signals to the LCD. There doesn't
    seem to be a regular line or frame pulse. There are intermittent signals on
    several lines, which is probably the phone updating its time display. If I
    could find out what controller is on the LCD, I could probably
    reverse-engineer the pinout.
    Right, FRM (or at least that's what Epson calls it). On the grayscale model,
    I need either 4 or 8 grays; e.g. black, 66%, 33%, white. Not 4 or 8 _bits_
    of grayscale resolution :)

    The common CSTN cellphone LCDs are 4K colors (4 bits per color component),
    which is perfect for me.
    It's not feasible. I don't have time budgeted for developing this function,
    and this is a black-box prototype that will have no relationship to the real
    hardware, so I'm unwilling to spend lots of time inventing wheels that will
    be discarded. Plus, I don't have much experience with VHDL (most of the
    projects I've done with CPLDs have been with schematic-entry packages).

    The real product would probably use an ASIC/ASSP with a 65C02 or 65C816 core
    and on-chip LCD controller, with a custom LCD. But that is not my problem; I
    will provide technical advice to the customer and that's *it* - I'm not
    getting roped into writing the actual code for the real product, because
    they would probably want to pay me on a royalty basis, and I don't believe
    this product will be cheap enough to enjoy widespread sales. They want a
    QCIF color CMOS image sensor, a color LCD, IrDA connectivity and 1Mb of
    internal flash memory for a retail price of $30. I don't believe they will
    be able to sell it for less than $100.

    I gave the customer an estimate based on the assumption of being able to
    source LCDs with on-board controllers. If that turns out to be an invalid
    assumption, I'll just cancel the contract. It means throwing away some R&D
    time, but that's just a risk of doing business. Hantronics does sell a color
    LCD with on-board Epson controller, but it's a bit large for my needs.
  7. John Atwood

    John Atwood Guest

    This is perhaps a reach, but for the prototype, you might consider IR'ing
    images to one of those wrist cameras:

  8. This is perhaps a reach, but for the prototype, you might consider IR'ing
    A wrist camera is the product I'm prototyping ;) I don't believe they will
    cost it down to their target, even with a crappier LCD.
  9. Perhap this is what you need:

    SAN JOSE, CA, September 23, 2003 . . . Atmel® Corporation (Nasdaq:
    ATML) announced today the introduction of a new family of digital
    camera processors that cover the entire market for Digital Still
    Cameras (DSC). The AT76C113 family of products integrate all the
    functions required to implement digital cameras on to a single chip.
    The device performs the functions of capturing, processing,
    compressing, displaying, and storing images in flash cards, as well as
    controlling camera functionality through the use of an integrated
    ARM7TDMI™ processor. In addition, the ARM processor is
    responsible for analysis of a scene, through hardware assist, and for
    the fine-tuning of image processing algorithms that enable consumers
    to take exceptional pictures. AT76C113 devices support all flash card
    interfaces including Secure Digital, MMC Multimedia Card,
    Memorystick™, Smartmedia™, CompactFlash™, and Atmel
    Dataflash® cards. AT76C113 has a direct interface to NAND-flash
    devices that allows program code as well as captured media to be
    stored in on-board NAND-flash. This potentially eliminates the need
    for shipping removable flash cards with a digital camera, which in
    turn would reduce end-product cost. In addition, all necessary
    peripherals including TV video output, USB, UART and SPI, digital
    audio interfaces, and direct interfaces to popular LCDs have been
    integrated to minimize the total system cost. Analog to digital and
    digital to analog converters have also been integrated to detect,
    measure, and recharge batteries, to capture and playback audio without
    the need of external components, and to control lens motors. Certain
    parts also contain USB hosting is also available on allows cameras to
    directly print pictures to photo printers.

    All AT76C113 devices support MPEG video multiplexed and synchronized
    with MPEG audio at a resolution of 30fps quarter-VGA resolution. They
    can also decompress audio files, including MP3, through a
    high-resolution digital audio interface. The unparalleled image
    processing performance- of 55ms per megapixel, and the compression
    speed of 75ms per megapixel, combined with the high transfer rates to
    flash cards, can achieve capturing, processing, compression, and
    storing of six megapixel images in less than one second with minimal
    power consumption. A two-megapixel AT76C113-powered camera can take
    over 600 pictures using a pair of regular size Photolithium-type
    batteries with strobe and zooming for every shot. Typical camera use
    can exceed 1000 pictures per battery.

    The family of AT76C113 contains products for low-end cameras limited
    to three megapixels and products for high-end cameras from four to six
    megapixels. Both low and high-end products are available with and
    without USB hosting capability.

    Production samples, evaluation boards, software libraries, as well as
    full application software are available now. Production is ramping up
    now in support of several digital camera manufacturers.

    Pricing will be under $8 for quantities of 50,000 parts
  10. Cameras (DSC). The AT76C113 family of products integrate all the
    Yeah.... good luck trying to prototype anything around this part, though. I
    don't even know who the financial backer of the project is, but I am pretty
    sure the idea isn't coming from one of the big names in toys.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day