pic programming

Discussion in 'Embedded Systems and Microcontrollers' started by topstuff, Nov 3, 2011.

  1. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Hi, I am a keen amatuer electronics enthusiast, and one of my main interests is LCD TVs (I do realise this isn't a TV repair forum I know there quite a few out there, but this is a specific problem), I have repaired a few up to now, mainly SMPS problems with some success ( I am learning all the time..)..Any way I am on my next project, and my experience at the moment fails me, I have a TV with a pic problem (TV stuck in standby doesn't turn on), I have reset the pic (the usual join pins 7 and 8 together and switch on) and sure enough it worked and for a while a very happy man I was too..however when the TV was turned off and turned back on I had to carry out the same reset procedure, and it worked fine again in fact over a period of 5 or so days I haven't had to do it again ..but of course you can say with certainty that it will happen again..So, what I need to do is transfer the data from the old pic to a new one. I am hoping it is a simple case of obtaining a pic programmer, inserting the old chip, read the data, store it, put the new chip in the programmer and write the data to the new chip..To me it sounds good so far, I obviously am not going to do any programming my self (I wouldn't know where to start yet, and I suspect there is a lot of complicated code on the pic)just a straight transfer of data.. Sorry for the long preamble but this is my question. I need to read and reprogram a 24C32WP pic chip, what pic programmer would I need (cost as always is a factor the cheaper the better, and I live in the UK)and what are the steps involved? I would attemt to do it under my own 'steam' but what concerns me most is the accidental erasure of the data on the original pic, if that happens then the TV is junk...Thanks in advance for any help
     
  2. sheldons

    Active Member

    Oct 26, 2011
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  3. t06afre

    AAC Fanatic!

    May 11, 2009
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    I will guess the chip is code protected. So depending on type it may be hard to salvage the program data. This is just meant as heads up. You do not know if the chip is protected before you try to read it.
     
  4. Markd77

    Senior Member

    Sep 7, 2009
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    Last edited: Nov 3, 2011
  5. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Hi,Sheldons thanks for your reply(and everyone else too)the tV is a daewoo DLT-37C3FTB and a rom file for that model/chip would be great, however from your post you imply that the programming is done in situ is that right?

    t06afre:I have been reading about pics and programming them etc, but I have not come across the read/write protect code you mention, my local TV shop repair man has told me of the procedure (my first post) and he did not mention this (I can only ask him so much,i did not want to out stay my welcome)Thanks Regards
     
  6. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Markd77
    Hi,Just seen your message about sending you a chip to try and program, that sounds good to me, I can certainly send you one to keep they are cheap enough, but can you bear with me for a while because i have got to purchase some first.. Many thanks..Regards..when I get some i will contact you for address etc..BTW the chip fitted in the TV is DIP not SMT so no probs there..
     
  7. AlexR

    Well-Known Member

    Jan 16, 2008
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    The 24C32 chip is a I2C interface serial eeprom and as such there is no way it could have any code protection.
    The Microchip PICKIT2 programmer does support I2C eeproms but PICKit3 does not. Support in PICKIT3 seems to be on their "to-do list" but as the its been 3 years since the release if PICKIT3 I wouldn't hold my breath waiting for PICKIT3 support.
     
  8. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Hi AlexR
    Thanks for your reply it is most helpful, now I know the equipment I need, and the info on the code protection is good too, I won't have to worry that I can't even get started, I will have a whizz round the internet and get one..Once again many thanks..BTW I think I am going to have a go at it by myself,as I said in my first post my biggest worry is that I might inadvertantly erase or over write the original data on the pic that I want to read,so apart from the obvious, like not clicking WRITE or ERASE in the programming software is there any precautions I should take? Thanks..Regards
     
  9. Markd77

    Senior Member

    Sep 7, 2009
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    I've never actually done it so a bit of a search around might be a good idea. I would think, just make sure the chip select lines are correctly set to the same logic levels as they are in circuit, and read the chip a few times to make sure the output is always the same. If there's a dodgy byte or two they might read differently on occasion.

    If you think you will be doing this sort of thing a lot then the PICKIT2 might not be the best choice because it only does a small variety of eeproms, but dedicated eeprom programmers typically cost over double the PICKIT2 price.
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Your problem may be bad capacitors, and it was coincidence that it worked when you removed power for a while and tried again.

    Look on the power board for any buldged top capacitors, or any that are leaking around the leads (a brownish fluid, looks like solder flux). I've fixed several displays for friends with equal value, higher voltage Low ESR caps, typically 4-8 per display, total around $8-$12.
     
  11. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Hi,thatoneguy
    Many thanks for your response. I am quite familiar with the caps problem, I myself have indeed repaired a few TVs with that very problem a Samsung(notoriuos-for-it) lcd monitor which I am using now and a very nice LG 37" (£30)TV which I now use in my front room.
    On the Daewoo my first port of call was the power board, and after some head scratching and changing some components it was very clear that the PSU was not at fault,as I said in a previous post the shorting of pins 7 and 8, which resets the eeprom (a known fix) cured the problem,for now any way, in fact after having done that a few times the tv hasn't done it (won't switch on)since..I would refer you to my previous posts as to my intended course of action..Thanks ..Regards

    topstuff
     
  12. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    HI, Again just an update, thought i'd let you know how I was getting on with the pic prob,after spending some time and thought on it I have come to some conclusions (speculation), that the chip itself may not need programming in a stand-alone programming unit, on recollection I did repair a computer monitor by replacing the eeprom with out programming it, just soldered it to the board (SMT job)and it programmed itself in situ and the monitor worked perfectly, after reading info from the data sheet regarding the 24c32wp, it kinda seems that it is programmed by the surrounding software/hardware on the signal board, I suspect the chip stores continually changing information such as volume settings, brightness, contrast, etc, and as the data that controls these functions is continually changing the chip must be being read and written to all the time that the TV is working...In conclusion I am just going to buy a chip and solder it in to the board and see what happens..I will let you know how I get on..Thanks everybody for your time in writing replys I am most grateful Be in touch soonish with a result ..

    Regards topstuff
     
  13. topstuff

    Thread Starter New Member

    Nov 3, 2011
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    Hi, Another update,thats if any one is still reading this thread, as I said in my previous post I would just solder in place a new 24c32 pic and see what happens,well thats just what i did, and joy of joy the TV came on straight away and works perfectly:D, I must work on my soldering skills though:(, I struggled to unsolder the old chip without causing damage to the PCB ( there are some very fine copper traces on the board), and when I came to replace the chip I put a 8 pin socket header on the board (just in case), so if your in a similar position then solder in the new chip and away you go. Any way once again thanks to all those who took the time to reply TTFN

    topstuff
     
  14. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Thank you for the update!

    I very much like it when members return to post if a solution works or not, as it helps everybody help others more.

    I myself doubted the EEPROM was at fault, so I'll be having Crow for breakfast.

    Tip for SMD: Usually, most new electronics use lead free solder. If you aren't using lead free, add a bunch of your solder to the lead free, then remove component, and solder wick away all the lead free solder you can.

    Then, GET A FLUX PEN and use it liberally, then solder in the new component. The other biggest problems people have is adding too much solder, this is easily solved by using solder with diameter < 0.020", it's like heavy thread, but adds enough solder for a SMD making it a little more difficult to add too much. If you do add too much, solder wick is your friend. Order flux pens and solder wick in 5 packs or more for cheaper prices (if you do a lot of work/rework).
     
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