Hacking a Salvaged HP Deskjet or All-In-One Display

Discussion in 'General Electronics Chat' started by madsi, Mar 24, 2015.

  1. madsi

    Thread Starter Member

    Feb 13, 2015
    107
    6
    I have been given several kinda new and some a little older HP inkjet printers that have small but nice VGA-like color displays on them. The printers need ink or have other problems, but the displays on them work perfect.

    I have a project that needs to display many lines of info at once, all I see ready made on Ebay is 20x4 LCD or 128x64 pixel displays.

    Does anyone have any experience hacking any of these neat looking small displays to work at a new job?

    Is there a cheap alternative if this is a dumb idea?
     
  2. OBW0549

    Well-Known Member

    Mar 2, 2015
    1,300
    879
    I don't have any experience hacking displays, but my guess would be that unless the display and its driver are identifiable industry standard types (i.e., not custom designed by/for HP), AND you can get them both out of the printer intact and functional, you could be in for quite a frustrating project.

    Adafruit.com (and others, I suppose) sells color TFT displays in various resolutions, packaged as add-ons for Raspberry Pi's and Arduinos; maybe one of them could be adapted to your purpose?

    That's all that comes to mind...
     
  3. madsi

    Thread Starter Member

    Feb 13, 2015
    107
    6
    Thanks for your advice, OBW0549.
    I just saw the Arduino shields, look pretty interesting, but when I looked at the supporting code libraries, they were complex and so a little daunting. I think it would take a long time to convert the code logic into PIC compatible code.

    I wonder how hard it would be to code to do text on these displays, graphics are not so important.. besides, I just need a multi-line text display with a smaller footprint MCU interface, like the PIC chips I am playing with, I don't want to Arduino. Using an Arduino board would make the whole project just too large and bulky and I would have to start over again with the coding and hardware.

    Hasn't anyone else built a PIC MCU project that really needs to display a lot of data?

    Right now I am displaying data on a laptop interfaced to the CPU, but I want to make my
    robotic project into a single integrated unit. I have a lot of "flat" low-profile room, but I just don't want to glue or screw a laptop on top of my project for the sake of a display.
     
    Last edited: Mar 24, 2015
  4. OBW0549

    Well-Known Member

    Mar 2, 2015
    1,300
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    I have one of the little 1.8" color displays for the Arduino, and as far as I could tell by briefly looking at the libraries, they do character display by writing the characters as bitmaps; the display itself is purely graphic. I agree, it would probably be a big job converting their libraries to something usable on a PIC.

    I did a bit of poking around on digikey.com, and didn't find any LCD or VFD character displays larger than 4 lines X 40 characters for less than $100. Plenty of 4X20 and 4X40 displays, all in the vicinity of $25, but nothing larger.

    :(
     
  5. madsi

    Thread Starter Member

    Feb 13, 2015
    107
    6
    I just opened the "text" library..looks so simple, works with a 1.8-in graphics display available on Ebay.
    The devil is in the details of TFT.h since SPI is something I already have some code that works.

    #include <SPI.h>
    #include <TFT.h> // Arduino TFT library

    #define cs 10
    #define dc 9
    #define rst 8

    TFT screen = TFT(cs, dc, rst);

    void setup() {
    // initialize the screen
    screen.begin();

    // make the background black
    screen.background(0,0,0);

    // set the text color to white
    screen.stroke(255,255,255);

    // write text to the screen in the top left corner
    screen.text("Thanks OBWo549!", 0, 0);
    }

    void loop() {

    }
     
  6. DNA Robotics

    Member

    Jun 13, 2014
    122
    26
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