1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

in trouble with LCD (JHD162A)

Discussion in 'Microcontrollers' started by smileguitar, Dec 18, 2007.

  1. mvs sarma

    mvs sarma Well-Known Member

    Joined:
    Oct 29, 2006
    Messages:
    3,512
    Likes:
    76
    Location:
    Hyderabad, India.
    I understand Eric,
    Wish you all A Merry Christmas
     
    Last edited: Dec 23, 2007
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    Many thanks... Wishing you a Prosperous New Year!....:)
     
  3. mvs sarma

    mvs sarma Well-Known Member

    Joined:
    Oct 29, 2006
    Messages:
    3,512
    Likes:
    76
    Location:
    Hyderabad, India.
    I used JHD162A display earlier. I used a 10 ohm resistor and worked fine. this might help you in settling the resistor value. the pot used for contrast could be replaced with 10K and 1K2 (lower value towards Vss). this will not leave things to chance for the O P
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0

    I'm upset now, the LCD still not displaying any character. I tried to connecth the backlight with resistor, nothing display at all. Then I changed output port, cannot work as well. I change the breadboard I used also not function. All the possiblity that may cause the LCD not working have been try.... What should I do now? change a new LCD?

    Thanks!!
     
  6. mvs sarma

    mvs sarma Well-Known Member

    Joined:
    Oct 29, 2006
    Messages:
    3,512
    Likes:
    76
    Location:
    Hyderabad, India.
    don't be upset for every failure. this is where you really learn, hardware or software- if everything works as you wire- there is no learning-- FINE--

    check with ref to pin1 of LCD the DC voltage on pin3of the LCD.
    it should be around 0.8 to 1.4 V Dc approximately.
    if it is more , it will show all dark rectangles( each character is made up of 5*7 dots which forms a rectangle) under situations all the 35 dots will turn dark. like that all 16*2 characters turn dark rectangles.it should be adjusted around 1V+/- 0.25

    then the display will come up.

    then check up the connections for correctness and for dryjoints.
    try to connect a 0.1uF capacitor across pins 1&2 of the LCD .
    i have used it across various softwares and it works.

    however please check whether any of the COBs(Chip On Board) on the back of display is WARM or HOT. this happens if you have pulled out the display while it is working.(NEVER DO IT IN FUTURE) If so, I feel it should not happen, the display has gone and you may have to replace. please give a feed back.
     
  7. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    Really thanks for your advise. I'll give you a feed back soon. Thanks...
     
  8. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    Sorry for late reply since recently is quite busy for other assignment.

    I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

    Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?

    Thanks!
     
  9. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    hi,

    >>I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

    Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?


    If you are trying to run the program I posted 'lcd2line1', that works OK in the PIC.
    Its most likely you have a problem in your hardware.

    I have found that different LCD's do have a different pixel block contrast level.

    As I suggested, write a simple LED ON/OFF program and prove the hardware for the remainder of the project.. once you are sure the project works without the alpha-numeric LCD, then you can get an idea if the LCD is faulty or not.:)
     
  10. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    hi,

    >>I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

    Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?


    If you are trying to run the program I posted 'lcd2line1' that works OK in the PIC. It most likely you have a problem in your hardware.

    I have found that different LCD's do have a different pixel block contrast level.

    As I suugested, write a simple LED ON/OFF program and prove the hardware for the remainder of the project.. once you are sure the project works without the alpha-numeric LCD, then you get a idea where the problem lies.:)
     
  11. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    Sorry, I have forgotten to mention that I didn't use your programme today because it's quite confusing. Today I had tested the hardware with a simple LED ON/OFF programme. LED works, but LCD not. Also, I used LED to test my LCD programme that I've slow down the delay time, the result is just like what I had set. But LCD still doesn't work......:( :confused:
     
  12. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    hi,
    For the LCD test, you dont have to understand my program, just assemble it and load the hex file into a PIC and run it.

    I am beginning to suspect your LCD is faulty.
     
  13. Pommie

    Pommie Well-Known Member Most Helpful Member

    Joined:
    Mar 18, 2005
    Messages:
    10,162
    Likes:
    340
    Location:
    Brisbane Australia
    Am I right in thinking you have no connection from pin 1 to ground but instead have a capacitor?

    You should have,
    Pin 1 to Gnd.
    Pin 2 to Vcc.
    A capacitor from pin 1 to pin 2.

    Mike.
     
  14. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    I see... I think I should connect by this way, why I never think of it. Oh my god, I'm totally lost....

    Thanks for your suggestion!
     
  15. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    You mean my LCD is malfunction? But the light can be on, and some dark rectangles appear then faded down......
     
  16. mvs sarma

    mvs sarma Well-Known Member

    Joined:
    Oct 29, 2006
    Messages:
    3,512
    Likes:
    76
    Location:
    Hyderabad, India.
    Aa I have indicated last time, generally the failure is also indicated by additional warming-up of one of the COBs behind the JHD162A.

    This happens ( at leat happened to me) when a display is inadvertently plugged out when the device is working-- plug and play culture.
     
  17. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    COBs behind the JHD162A is slightly warm mean the LCD is burnt? Even it still can on the LCD light?
     
  18. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    This is what we are trying to find out!:confused:

    Whats the problem in loading my hex file that works when loaded into a PIC, for driving a HD44870 LCD controller????

    At least try it.!:)
     
  19. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    Hi, can I know how I test the LCD is faulty or not? Tomorrow I'll buy a new LCD to test it, but before change a new LCD I need to know how to test LCD is either in good condition or not because I need to write a report and prove that LCD is faulty.

    Thanks in advance!!!
     
  20. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

    Joined:
    Jan 4, 2007
    Messages:
    21,241
    Likes:
    645
    Location:
    Ex Yorks' Hants UK
    ONLINE
    Have you tried a known working LCD driver program???
     
  21. smileguitar

    smileguitar New Member

    Joined:
    Dec 17, 2007
    Messages:
    39
    Likes:
    0
    Sorry, what do you mean a known working LCD driver programme? I think I never tried it before. Really sorry, this is the first time I touch LCD and not really know about the well known LCD driver programme. erm... How it is try...

    Thanks!!
     

Share This Page