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Thread: The meanings of the LCD command bits

  1. #1
    Join Date
    2006/11
    Posts
    4

    The meanings of the LCD command bits

    I am using a 20X2 LCD, using 4-bit mode. I don't understand all of the command bits used in the initialization.

    For instance,
    After writing one character in the first position, I would like the cursor to auto-increment to the second position. Does this mean I should set the "I/D" bit in the "entry mode" command?

    I would like to hide the cursor so that the user can not see the cursor at all. Does this mean that I should clear the C and B bits in the "Display ON/OFF control" command?

    In the "Cursor or Display shift" command, what exactly are the "S/C" and "R/L" bits used for? I don't understand the explanation given in the datasheet.

    I'm close to getting the LCD screen to work, but right now, all I get is a bunch of dark blocks in the second row when I power up my unit. Thank you for any help!

    -Richard

  2. #2
    Join Date
    2003/11
    Location
    Western WA, USA
    Posts
    1,148
    Quote Originally Posted by rtarbell View Post
    ... but right now, all I get is a bunch of dark blocks in the second row when I power up my unit...
    Sounds like your initialization sequence is not working.
    Code:
    I/D = 1 : Increment	I/D = 0 : Decrement
    S = 1 : Display Shift On
    D = 1 : Display On
    C = 1 : Cursor Display On
    B = 1 : Cursor Blink On
    S/C = 1 : Shift Display	S/C = 0 : Move Cursor
    R/L = 1 : Shift Right	R/L = 0 : Shift Left
    DL = 1 : 8-Bit		DL = 0 : 4-Bit
    N = 1 : Dual Line	N = 0 : Single Line
    F = 1 : 5x10 dots	F = 0 : 5x8 dots
    BF = 1 : Internal Operation
    BF = 0 : Ready for Instruction
    Infinity or Bust

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