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Serial LCD Backpack — Parallax Forums

Serial LCD Backpack

CumQuaTCumQuaT Posts: 156
edited 2009-03-11 18:13 in General Discussion
Hi all.

You may have noticed that Parallax LCD screens come with wonderful little serial backpacks that give you easy 3 pin communication to the LCD unit. Unfortunately, not all LCD screens come with this, so I was wondering if anyone knew of a good circuit that I could follow to build myself one of these little accessories?

Thanks in advance.

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Comments

  • MikerocontrollerMikerocontroller Posts: 310
    edited 2009-03-02 07:22
    · I found this on the Kronos Robotics website: http://www.kronosrobotics.com/Projects/Athena%20Serial%20LCD.pdf
  • CumQuaTCumQuaT Posts: 156
    edited 2009-03-02 07:30
    That's a really good circuit, however, I don't have an Athena programmer... I mostly work with PICs and Basic Stamps with my work... Any chance of a PIC based one? I've Googled my butt off looking, without much success, but perhaps I'm looking for the wrong things...

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  • CumQuaTCumQuaT Posts: 156
    edited 2009-03-02 07:40
    Hey, I found this document:

    http://www.wulfden.org/downloads/manuals/K107manual.pdf

    Which has enough in it for me to at least work something out that should work pretty close... Just need to sort out coding the PIC to do what I need it to do... That's the fun part I guess...

    If anyone can find a pre-designed circuit (preferrably a 3 pin serial interface) with code ideas for the micro, that'd be awesome!

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  • MikerocontrollerMikerocontroller Posts: 310
    edited 2009-03-02 08:25
    ··· How about this.· Uses a PIC 16F688.· Schematic and source code included.·
    http://www.sparkfun.com/commerce/product_info.php?products_id=258
  • CumQuaTCumQuaT Posts: 156
    edited 2009-03-02 08:52
    Flawless!

    That's exactly what I'm after! Thanks very much!

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  • ForrestForrest Posts: 1,341
    edited 2009-03-02 12:01
    The K107 kit is also a good choice. The board and chip is a good deal at $9 if you already have the other components www.wulfden.org/TheShoppe/k107/k107.shtml

    If you're connecting this to a Basic Stamp, use the 9600 baud version
  • UghaUgha Posts: 543
    edited 2009-03-02 13:51
    I'd recommend the #117 kit http://www.phanderson.com/lcd106/lcd107.html
    It costs $6.95 USD and has additional features like custom characters, bootup screen, Big numbers mode (if you have a 4x20 screen), variable backlight and 4 general purpose output pins.

    It is a kit, and doesn't come with a board. You'll either have to breadboard the components or stick them on a piece of perf board like I did.

    It will support any microprocessor that can output a 9600 baud serial communication.
  • ZootZoot Posts: 2,227
    edited 2009-03-02 13:56
    You can also use an SX and a few resistors. The SX help file includes the schematic and ready-to-run source code for setting up a parallel LCD as a serial LCD. Excluding the cost of the programmer (SX-Key) this would probably cost you about $6.

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    1uffakind.com/robots/povBitMapBuilder.php
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  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2009-03-02 14:43
    The cheapest standalone backpack I have done has got to be the simplest and cheapest I reckon. In one job I used an 8-pin PIC such as the 12F629 etc. I had the LCD connected in 4-bit mode so that the PIC would drive D7..D4 and EN directly. The R/W was tied low and the RS (or A0) was connected to an RC network hanging off one of the data lines. The PIC has one spare pin which is an input so that was made the serial input. The receive routine was bit-bashed of course and there was enough time between characters (52us @19200) to write the information to the LCD. Most of the time the RC circuit was precharged high as most operations involved writing data.

    So the PIC handled the asynch data and control whether it was direct or RS232 inverted. In fact the application was an engine monitor wherein the serial input was actually a pulse input.

    LCD CONNECTIONS to PIC12F629

    D7..D6
    GP0,GP1,GP2,GP4
    RS ................ GP4 via RC
    LCDEN.......... GP5
    R/W.............. GND

    Totals LCD backpack parts:
    1x 8-pin PIC
    1x resistor
    1x 1000pf capacitor

    *Peter*
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-03-02 19:31
    If you have an SX28 and an SX-Key you can make one for free. See the example application in the SX/B Help File for a circuit that is compatible with the SEETRON spec. Take care.

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    Chris Savage
    Parallax Engineering
  • CumQuaTCumQuaT Posts: 156
    edited 2009-03-03 01:09
    Sounds pretty cool to me. There's some great options here. Thanks for the info!

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  • ForrestForrest Posts: 1,341
    edited 2009-03-07 12:37
    Gracey,

    This discussion has been about HD44780 based LCD character display's. These small displays typically have 2 or 4 lines of 16 to 40 characters.

    Forrest
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2009-03-11 18:13
    Forrest...Spammer Gracey has been removed. =)

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    Chris Savage
    Parallax Engineering
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