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Thread: Which touchscreen type to use

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  1. #1

    Default Which touchscreen type to use

    I am looking to build a touchscreen based project. It is to be a valve based machine controlled by the touchscreen interface.

    Initially my plan was to use a 240x128 or a 320x240 LCD with a resistive 4wire screen, controlled by the ATmega32. I was quoted 2250 and 3500 for the screens respectively and 1300 for the touchfilm.

    So far, I have these options to consider:
    1. Should I go with the physically larger [and more expensive] monochrome GLCD? [Cost = ~4K] [Can use a familiar AVR platform]
    2. Should I consider the TFT module with the Atmega. For effective control of the display should I consider move to an ARM based platform. [Cost =~4-5K ] [Need to learn new platform]
    3. Should I cover a regular monitor with Touchfilm and try the VGA interface? [Cost =LOW [second hand monitor] ][Can the AVR deliver?]
    Last edited by shaunakde; 01-23-2011 at 02:54 PM.
    Cheers,
    Shaunak.
    Feel free to PM/email me.

    Visit me sometime @ http://shaunak.ws

  2. #2
    Administrator T-1000 vikas's Avatar
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    Some questions -

    Is product to be mass produced ( what do you wish the per unit cost to be ) ?
    How far back the operator needs to see the screen, any viewing angles involved ?
    How much time do you have for first prototype ?
    What refresh rates of information are you looking at ?
    Any budget constraints for you ? As Dev boards might cost more than final proto

    Let me know ...
    Vikas Patial

  3. #3

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    Is product to be mass produced ( what do you wish the per unit cost to be ) ?
    Not likely.

    How far back the operator needs to see the screen, any viewing angles involved ?
    Screen will be mounted at ~ 4 ft, so no real angles involved.

    How much time do you have for first prototype ?
    One and a half year.

    What refresh rates of information are you looking at ?
    Fluid flow level and temperature to be refreshed atleast once a second. [Quite slow]


    Any budget constraints for you ? As Dev boards might cost more than final proto
    ~12K for the prototype + 3~4K for additional development materials we may need. That would include devboards and test equipment.

    There are 5 solenoid valves involved, which would consume the major portion of the budget. [We plan on buying the solenoids and milling the valve structures ourselves.]

    Ps: We have a number of atmega 16s with us, so using multiple m16s is an option too. (and Will be cheaper, possibly)
    Last edited by shaunakde; 01-24-2011 at 12:07 AM.
    Cheers,
    Shaunak.
    Feel free to PM/email me.

    Visit me sometime @ http://shaunak.ws

  4. #4
    Administrator T-1000 vikas's Avatar
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    12k is a little less to get into touch screens but anyhow with right pointers ull manage in much less ...

    You can go for GLCD but they are like OLD Stuff now ... go for TFT ... Brilliant colors and displays at a little extra costs ... really cool interfaces can be made.

    Buy a 3.2" TFT Screen either of the links below will do ( free shipping from this guy takes about 2 weeks + to deliver ) ( 3.2" gives VFM )

    http://cgi.ebay.com/3-2-TFT-LCD-Modu...item2ead465ff4
    http://cgi.ebay.com/3-2-TFT-LCD-Modu...item2c57cf0ce2

    The two panels above are supported by microchip advanced graphics library which has widgets making ur job super easy. Buy a pic24/32 and build your system around it.

    So final system will be -

    Your valves + one of the above displays + PIC24/32


    Why im recommending PIC is because it comes with free Graphics library which has drivers for LCD's i just recommend. And 80% of your coding effort will be taken care of with existing code from PIC. Also for your requirement free 64k PIC compiler will do fine.

    The total development time of a basic Touch based controller should take < 2 - 3 weeks with alll the hardware in place.
    Vikas Patial

  5. #5

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    thanks vikas.

    Actually the funny thing is glcds are coming more expensive than Tfts!
    (joys of mass production)

    I Will go for it.

    If we do extend the budget a bit, any recommendtions for ARM boards?
    Cheers,
    Shaunak.
    Feel free to PM/email me.

    Visit me sometime @ http://shaunak.ws

  6. #6
    Administrator T-1000 vikas's Avatar
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    ARM is cool but more work is required .

    STM32 - could not find any free source of graphics library or driver ( All bits and pieces )
    LPC - though LPC1768 can be clocked at 100 Mhz , you will need to write a lot of code same as STM 32
    LM - Though graphics library is available , Its basic compared to PIC and LCD drivers are not there for cheap TFT's.

    There are paid professional libraries which will offer same and more than PIC's free stuff ... but they are way out of your budget.

    For dev board STM32 based are available on Ebay with touch screen ( same vendor links i recommend touchscreens from ) , locally ngx sell Blueboard based on Cortex M3 LPC1768 ( same which the mbed uses )

    ARM 9 will be an over kill and just spike the costs .

    I would recommend keep the costs low and turn around time less.
    Vikas Patial

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