+ Reply to Thread
Results 1 to 3 of 3

Thread: lcd delay time

  1. #1
    Join Date
    Mar 2014
    Location
    Pakistan
    Posts
    19

    Default lcd delay time

    i have tried serial 16x2 with 9600 buad and alpha 16x2 with 16f73 but both take much time to print,serial takes 15ms and alpha takes 4ms to print,is there any way to print on lcd in less than 200us by changing hardware or software?thanks

  2. #2
    Join Date
    Oct 2005
    Location
    Sweden
    Posts
    3,196

    Default Re: lcd delay time

    If you look at the datasheet for the 44780 controller you can see the timing requirements, not all "compatible" controllers are equal though which is why PBP has the DEFINE LCD_COMMANDUS and LCD_DATAUS.
    The defaults for those are 1500us for a command and 44us for each data byte. So if you do a clear screen, write 16 characters, move cursor to second line, write 16 characters that's a total of 1500+(16*44)+1500+(16*44) = 4408us which is pretty close to the 4ms you mention. You can always try lowering the timing values and see where it stops working.

    For a serial LCD it obviously depends on the baudrate but it TOO has to write to the LCD which will then take those 4ms.

    One way to get around that would be to do a buffering serial LCD controller. You could then send it data at a very high baudrate and it would then update the screen while the main CPU does other things. Or be clever and only write to the screen when and where data actually changes.

    /Henrik.

  3. #3
    Join Date
    Aug 2003
    Location
    Australia
    Posts
    980

    Default Re: lcd delay time

    Obvious answer is to toss the serial LCD backpack and use the HD44780 parallel interface, if your chip has the IO to afford it.
    Some can play up if you didn’t give the LCD it’s delay time at first startup.

Similar Threads

  1. Actuating Servos on a Schedule/Time Delay
    By wdmagic in forum mel PIC BASIC Pro
    Replies: 1
    Last Post: - 15th March 2013, 19:51
  2. Calculating time delay between two inputs?
    By grimmjow in forum General
    Replies: 11
    Last Post: - 18th October 2010, 14:52
  3. Need advice for creating nS time delay
    By sayzer in forum mel PIC BASIC Pro
    Replies: 28
    Last Post: - 12th December 2007, 07:34
  4. change in the delay in real time
    By manu123 in forum General
    Replies: 3
    Last Post: - 6th April 2007, 19:11
  5. Linx RF -> HSERIN time delay / time critical app...
    By batee in forum mel PIC BASIC Pro
    Replies: 1
    Last Post: - 15th October 2004, 15:04

Members who have read this thread : 19

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts