1. FroceMaster

    Thread Starter Member

    Jan 28, 2012
    402
    4
    Hi
    Have this setup where i have a 16F1509 to drive a 2*20 LCD.
    Works fine, but when i give it supply at 5,3V DC it's only first line of LCD that will light up.
    only Squares...
    When i connect it to 5,03 Vdc from PC it starts with one line of Squares and then goes to function correct on both lines.
    and keeps on running.

    Can post all code but i don't think it's in the code.
    The LCD Works to 7vdc max.
    16F1509 is max 5,5Vdc.
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,073
    3,856

    Do you have a potentiometer attached to the contrast pin ? Adjust as needed.

    Pin3 (contrast adjust) or Vee. Should be the wiper of a pot (other connections of pot to v+ and ground
     
  3. FroceMaster

    Thread Starter Member

    Jan 28, 2012
    402
    4
    sure i have, as you can read the system Works fine, but have now done something,
    put a diode in serie to drow the voltage, but same problem, could be the power is bad quality,
    is a wall adapter 230vAC to 5v Dc.
    will try to replace that if i have another.

    Edit, have switch to another wall adapter, same problem,
    Works fine when connected to 5v dc from PC USB.
     
  4. nerdegutta

    Moderator

    Dec 15, 2009
    2,519
    786
    Hi, perhaps it's a current problem. I believe the PC can offer a bit more current than the wall adapter.
     
  5. FroceMaster

    Thread Starter Member

    Jan 28, 2012
    402
    4
    dont think current problem, Circuit only use 2,45 mA. ;)
    Put a 2200uf cap on the powerinput and now it Works.
     
  6. nerdegutta

    Moderator

    Dec 15, 2009
    2,519
    786
    Great!

    Perhaps it was oscillating?
     
  7. Picbuster

    Member

    Dec 2, 2013
    376
    50
    You do have an other problem a huge cap 2200uf not a normal situation.
    Your problem might be gone but the source of your misery is still there.
    please get a scope and remove the cap and find out what is going on.
    what type of pwr circuit are you using? ( is difference between in and output within the spec's)

    I do have two displays 2 x 20 on one pic the caps are 3 x 10uF total but also 100nF parallel to each 10uF.
    the total pwr consumption( cpu/line drivers and GPS) without connected backlights for the displays 45mA approx.
     
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