DIY E-reader

Discussion in 'General Electronics Chat' started by phaseone, Apr 17, 2010.

  1. phaseone

    Thread Starter New Member

    Oct 18, 2009
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    Dear community;
    I have a large number of txt files on my computer that I have yet to read, but I dont have a laptop to read from when I travel. I also dont wanna drop the $200 for a legitimate e-reader. What im looking into is making a e-reader with a character LCD screen, an SD card, and some sort of microcontroller to run these things.

    Beyond that, i am at a loss. I have no idea what type of LCD screen to get and from where, and i have no idea of how to design the accompanying circuit though i assume it will have some sort of MUX/DEMUX in it. If someone could give me some ideas, i would be much obliged.

    Thanks,
    Julian
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    It'll cost significantly more to DIY an eReader. Get an iPad or Kindle or just print them.
     
  3. retched

    AAC Fanatic!

    Dec 5, 2009
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    If you were to use a small screen, like a qvga. You could do it cheaper.. not much, but cheaper.. That is if you dont include your time in the value.

    If this was text only. TXT file only, you wouldn't need a graphics driver or image processing, or PDF processing. So you could use a PIC, a compiler that has qvga libraries, and SD memory libraries to do it rather easily. The hardest part would be getting a file list off the sd card and selecting which file to load. If you opened a file that was larger then the memory you have available on the pic, you will need a way to open the txt file in blocks or chunks at a time that will fit in memory.

    Most qvga libraries and drivers will accept ascii input, and txt files are just that. No special formating or font types, so you could feed the file directly to the screen. Figuring the amount of characters per screen, and loading that amount of characters from the file and displaying them until a page up or page down button is pressed.

    By using this method, you dont have to worry about coding complex scrolling functions that would require more memory and such.

    So you could use a jog-wheel for UP/DOWN/select. If it was one of those jog wheels you can depress for a 3rd input. Or you would use 3 momentary buttons. Up - Down - and Select

    That will allow you to scroll through the directory listing, which would appear on power up, to select the file you wanted to view.

    Then they would act as page Up and Down and exit buttons. The up and down buttons would page through the file and the select button would return to the directory listing.
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Or get an eee netbook, the old 9" ones are pretty cheap.

    Without programming & electronics experience the OP is in for a very long ride.

    PS what does an Mux/Demux have to do with an eReader?
     
  5. phaseone

    Thread Starter New Member

    Oct 18, 2009
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    @retched: thats an interesting idea. I think ill use your simplified 3-button interface. the QVGA screen seems like overkill, though. I think it'd be alot cheaper just to use a character LCD screen ex. http://yhst-27389313707334.stores.yahoo.net/20chbllcd.html . It wouldn't look pretty, and id probably have to get a bigger one than 20x4 but it would be significantly cheaper and easier to implement.

    @blueroomelectronics: The EEE looks practical enough, but i still think i could do it cheaper. A DEMUX setup would be the most efficient way of running an LCD display. If controlled by a ripple counter and fed by a data stream from a microcontroller on the same clock pulse, a large LCD display can be run with minimal inputs at any given time.
     
  6. retched

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    I dunno, you can get a single color qvga for around the same price. Coding would be the same if your just sending ascii character codes and using pre-made libraries.

    I also have to disagree with the mux/demux idea. Why would you care about saving pins on a device that is using a dedicated uC?

    Also, you are going to use more code and more complicated algorithms to mux a LCD display. The drivers are already handling the screen layout and repetition rates. You only send the character. I dont understand why you would care how many inputs the lcd needed. If you are going to burn battery power doing the MUX processing, and you DONT need the pins for other options...why? Also It isn't the best or least pin using way of doing this. The least pins would be using a serial bus. Thats a lot less then the MUX idea.

    Here: About the same price as a 20x4 display. Color and serial bus. Cant beat that. It would be exactly like reading text messages on a cell phone.

    http://www.sparkfun.com/commerce/product_info.php?products_id=569

    This only needs 4 pins from the controller. You can use a new low-power usage 3.3v uC and use the same regulator for the screen. You only need 4 lines of code to send each byte, then loop that until the screen fill amount is met. Wait for button press if its up calculate and retrieve characters same if down.. If select, head to the menu.

    This also gives you the ability to view graphics and photos if you wish to add such functionality in the future. With a standard cell phone battery, you get super long life and the ability to recharge from any usb port.
     
    Last edited: Apr 17, 2010
  7. phaseone

    Thread Starter New Member

    Oct 18, 2009
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    Daggonnit, retched, you've outdone me. I wasnt planning on such a small screen (1.2"x1.2") but I wasn't aware that these things came so cheap. Ill keep looking for a larger monochrome model.

    Thank you kindly, retched. You've given me more than I could have expected.
     
  8. blueroomelectronics

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    Jul 22, 2007
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    If cheap is your goal old Palm Pilots are cheap as dirt.
    [​IMG]
     
  9. retched

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    I just want to see you do it. I would be elated to see this as a finished project.
     
  10. coldpenguin

    Active Member

    Apr 18, 2010
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    On a usability point of view, I would go for a larger display than 20x4, but I haven't ever seen any larger ones than that in character mode. 20x4 would irritate the hell out of me.
    A GLCD I have here, is somewhere along the lines of 21x8 characters in size. It /uses/ around 12 pins of the PIC I have. However, it would make reading a block of text less painful.
    There are libraries available for them, but the programming of a GLCD would be more involved than the programming of using a serial attached character LCD for example. But if you are considering using an SD card as the textual attachment, and reading FAT maybe?, then I don't think that a GLCD would be beyond you.

    I am running my GLCD with a 40 pin PIC 18F4455, with graphics enabled in the library (lines, circles) + text + number functions (sprintf for doubles) then this uses around 30% of the memory available.

    edit:
    There are also 128x128 GLCDs available, they slightly more programming, as the panels are effectively 64x64 chips, but might be even nicer to read on,
     
    Last edited: Apr 18, 2010
  11. retched

    AAC Fanatic!

    Dec 5, 2009
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    I agree. But there are already libraries and sample code for sending text to these devices readily available, using serial. You could EASILY change the code to display set chunks.

    Im thinking the hardest part of the whole project would be adding word-wrap. Now, you dont HAVE to, you could easily count the number of characters output, and send a CR every 21char. (Or however many characters fit on 1 line of whatever display you choose.
     
  12. coldpenguin

    Active Member

    Apr 18, 2010
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    Interestingly, the GLCD/library I am using, automatically does wrap to the next line, no requirement to do the CR.
    I thought I would check the number of characters last night by printing
    123456789012345678901234567890
    and it started with 234567890 on the second line automatically. I think that the [G]LCD is going to be a lot easier than the FAT/SD access
     
  13. retched

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    I agree. It will be easier. But the fat/sd is already been done in many samples. The EasyPIC 6 I have has a SD card reader adapter and the codes for it are simple.

    The hard part would be formating and the such.. I wouldn't go there. I would use pre-formatted cards or use a PC to format the card before the initial file copies.

    The menu will be the hardest part. But then again. There are a lot of touch screen examples out there that use menuing... So that already has a bunch of samples to choose from.

    As you start, Ill work side by side with my EasyPIC6 and use the touch screen for the controller. We will see what happens.. Keep me abreast of what PIC and screen you wanna use.
     
  14. naikai

    New Member

    May 12, 2010
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    Hi, I'm new to this forum.
    I came up with similar ideas a few days ago and I would like to know how is the process going on right now.
    Thank you all for these useful informations.
     
  15. retched

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    The OP is here today, maybe we will get an update.
     
  16. phaseone

    Thread Starter New Member

    Oct 18, 2009
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    Hello again,
    Sorry for being so quiet for so long. I recently ordered several PIC16F72 chips, and I am looking on eBay for GLCDs (eBay has thousands of them). ex. http://cgi.ebay.com/Sharp-LM24P20-2...ultDomain_0&hash=item230718445f#ht_500wt_1182

    I'm still not certain what I'll use for memory. It seems as if flash memory would be the best suited to the application, but I don't have much experience with flash chips.
     
  17. retched

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    Dec 5, 2009
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    Use a SD card.
     
  18. sandman67

    New Member

    Dec 23, 2010
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    I've been trying to assemble a 'franken-reader' for the past year or so from salvaged parts, & so far, that's all I've got... parts! LOL I have around a dozen assorted monochrome lcd screens from old laptops, word processors, etc., guts from little digital picture frames & those pocket memo 'pda-wanna-be's' that where all the rage the last decade. Together with boxes of accumeulated 'junk, battery packs, and enclosures.... & I'm still missing that magic ingredient to make something that works.... Talent. LOL :) Nuts & bolts machines I can do. Electronics, do me... ;) I mean, really... What's the hard part? A basic monochrome text viewer, with a stick or card port for memory, an on/off switch, & 3 buttons; up, down, select. Keep it in basic or dos, 256k rom, nothing fancier that a $5 pocket organizer from radio shack for brains ($1.99 on sale). Using this as a guideline, is there any reason a decent viewer can't be planned out & assembled from a couple trips to goodwill & the shack for UNDER $30? MABY up to $50 at most, IF you use fancier parts. Keep it limited to .TXT, or possibly a couple other of the most basic formats. Come on, one of you gifted engineers step up & earn your internet god-hood & make the rest of us dorks believe in Santa... :) You KNOW the first one to do it will make serious cyber history, ranging from Wiki to Make... :) Not to mention all the internets you could possibly spend... Better than wooden nickles, a tenth of the weight & volume, safer on the enviroment. Al
     
  19. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Like I said before, eReaders are getting cheaper every day. The amazing Kindle 3 with WiFi is only $139, in a year it'll probably be less than $100. The Chinese ones are cheaper still.
    PS Radio Shack will never carry the sort of parts needed to make an eReader.
     
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