LCD module shows READ ERROR frequently

Discussion in 'The Projects Forum' started by new122, Mar 27, 2013.

  1. new122

    Thread Starter New Member

    Feb 5, 2013
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    Hello All,

    We have one LCD module connected to controller PIC18LF6722. Recently we changed OLD obsolute Display with similar configuration(??) display. NOw often (not every time) we are getting read error when we swipe card.
    Any thoughts on Error cause and possible solutions.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Swipe what card?
     
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  3. new122

    Thread Starter New Member

    Feb 5, 2013
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    We have employee card which they will swipe and that LCD module will guide them for furthur instructions.
     
  4. tshuck

    Well-Known Member

    Oct 18, 2012
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    Are you sure it was migrated properly (connections, program, order of operation, etc.)?

    What is the protocol between the card reader and pic? Are you sure this connection is valid?

    What are the power requirements for original board, the old display, and the new display?
     
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  5. MrChips

    Moderator

    Oct 2, 2009
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    You will have to provide more info, circuit, photo or link to show the unit you are referring to.
     
  6. new122

    Thread Starter New Member

    Feb 5, 2013
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    Thanks :),
    I am not sure about that becuase it was done by one of our previous engineer. But after looking both LCD display datasheet , power requirement is same and connection also correct. Rest of things , I have to look. Will inform soon about outcome.

    regards,
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    So the new module says "READ ERROR"? Do you realize the module can only display what it was told by the PIC, and it is the PIC and the sensor that read the card?

    The LCD is working 100% Look elsewhere for the real problem.

    Your card reader may be old. Dirty. Worn. Heck, your employee cards may need replacement.
     
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  8. new122

    Thread Starter New Member

    Feb 5, 2013
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    Thanks all for your time.

    Here we are using same reader and same microcontroller with Old display and it is working fine. But when we change display to our New PN, it shows an error in 1 of 8 times duing Card Swipe.
    OLD Display PN # FDCC2004B-FLYYBW-51LU
    NEW Display PN # NHD-0420DZ-FL-YBW

    Please advice
     
  9. tshuck

    Well-Known Member

    Oct 18, 2012
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    ...and the PIC is using the same code? Are you using a software implementated communication protocol? Do you have a debugger that you van use to single step the code?
     
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  10. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Did you ever think that the problem with the card swipe simply started when you changed the display simply by coincidence? Or it could be that you disturbed a connection when changing out the display. Why not just swap displays back?

    Wiith the few details you posted it is completley impossible for anyone to help you. Even with more details it wil be hard. You need someone with troubleshooting experice to look at it.
     
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  11. new122

    Thread Starter New Member

    Feb 5, 2013
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    Thanks all for your inputs.

    Awaiting for display come back to my desk.(Prob tomorrow). Once I receive then will try to provide more information. SO far information given is based on discusssion with field technician on phone.
    Will keep posted about progress.

    Regards,
     
  12. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Just providing details on the display will not be good enough. You will need to provide a schematic on the whole system and most likely will need to take measurements. Folks here can help you with troubleshooting but you are going to have to do the heavy work.
     
  13. new122

    Thread Starter New Member

    Feb 5, 2013
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    Thanks Spinnaker,

    I am commited for heavy work. But as being in this field recently, can you please let me know what sorts of meausurment I need to perform apart from Electrical.
    I am plaaning to apporoach this way to this problem.
    1) I will start with new LCD and wanted to check exact error and
    2) I will replace with OLD display and check error repeated or not.
    3) If NO error repeated then I must look on New Display with LCD drivers need to program side.
    4) If error repeat then I will start look on PIC and Card Reader side.
    5) I never had experience on Programming side, so then we must need some expert support.

    Let me know what other information I can collect to know cause of error.
    Thanks in Advance !!!

    Regards,
     
  14. new122

    Thread Starter New Member

    Feb 5, 2013
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    We are using Clock and Data Protocol between PIC and Reader. This is working connections. Schematic will going to post soon.
     
  15. tshuck

    Well-Known Member

    Oct 18, 2012
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    Safe to assume I2C?
     
  16. JohnInTX

    Moderator

    Jun 26, 2012
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    Possibly but likely not. Most simple swipe readers have enough circuitry to recover clock and data from the Manchester (or other) coded stripe but just present it like that.. clock and data, no Start-stoP like I2C. Just shift it in and scan for the start pattern in the data stream. Sometimes, the readers do that for you if they know which encoding standard(s) the track uses, issuing clock and data as before but with without the extra stuff on the track.

    Assuming the hookup is correct and powered OK, if the OP's code is polling the reader, I'd wonder if its also polling display READY and the display is slower than the original, making him miss clocks from the reader. Unlike I2C, there is no way to pace the data, it comes as fast as the user swipes the card.

    What's the make/model of the reader?
     
    Last edited: Mar 30, 2013
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  17. new122

    Thread Starter New Member

    Feb 5, 2013
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    We have International Bar Code Card Reader Smart Prox J version.
    http://www.internationalbarcode.com/sproxj.htm

    Also here is the list of messages we are getting.
    1) Error Reading Card
    2) Wrong Card Type
    3) Unauthorized User

    Regards,
     
  18. RG23

    Active Member

    Dec 6, 2010
    301
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    Check the initialization routines for both the displays in their respective datasheets

    Usually different displays do not have the same initialization routine (IR) (Check the datasheets for both displays)

    Did you make that change in the IR part of program?

    To make it simpler first call the initialization subroutine for the new display in the main program

    Try to display some character like A or 1 on the display

    If you are able to do this then proceed with the further troubleshooting
     
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  19. new122

    Thread Starter New Member

    Feb 5, 2013
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    Hello RG23,

    Please find both dispaly IR routine as a PDF. I found some differnece in both display(Highlighted(.
    Does that make effect in Card Reading error?

    Please advice.
    P.S.:-I will have a Physical unit from tomorrow to perform actual testing.
     
  20. new122

    Thread Starter New Member

    Feb 5, 2013
    17
    0
    Hello All,

    So finally I got a hold off of our faulty unit, and we seen that as we remove LCD Display from Unit machine start work normally(Accept Card and Everything). So newer display causing an error for Card read and rest. As soon we put back old display it again start work normally. We checked with differnt card reader, differnt controller and found same error with newer display. Anybody run across this problem.
     
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