Thursday 10 September 2015

INTERFACING LCD TO 8051

         LCD (LIQUID CRYSTAL DISPLAY)


  • This LCD Display the characters so we called as also CHARACTER LCD
  • If we give liquid. It is "1" for  BLACKNESS, "0" for WHITENESS   
                                              BLACK=1
                                              WHITE=0
  • We are using 16*2 LCD
  • By using this 16*2 LCD,  we can display 16 characters in 2 lines
  • For a single character we have to use  5*7 pixels

LCD  pins:


  • LCD having 16 PINS, Each having specific function.
  1.   Vss  --  GROUND
  2.   Vcc  --   POWER SUPPLY
  3.   Vee  --  CONTRAST (Intensity of blackness of pixel)
  4.   RS  --   Register Select
  5.  R/W -  Read or write
  6.  E   --   Enable
     7-14  D0-D7  --   Data bus
     15  +Vref   --   black light  +ve
     16   -Vref   --    black light -ve


D7 Bit  we call as BUSY FLAG


* lcd having  2 memory's

      1. Data memory (Display data RAM)

      2. Command memory ( Character Generator  RAM )
         
*  If   RS=0 , we selected as a  command memory

* If  RS=1, We  selected as a data memory.

* E = 1, Then  the character will fetch from  lcd memory to 8051 port.

* E =0, Then the fetching will stop.

* Internally  LCD having  30 positions  for each line  but it display only 16 positions.

* When  the     1st line of  30 position is completed  then  the next character display at 2nd line of 1st
 position.

* When  2nd line of 30 position  completed , Then the next character can display at  1st line of 1st  position

* Internally  in LCD  lines are circular.




LCD COMMANDS:


0X01       :      CLEAR DISPLAY

0X02       :       RETURN HOME

0X04       :       DECREMENTED  CURSOR (  SHIFT CURSOR TO LEFT) 

0X06       :       INCREMENTED CURSOR   (  SHIFT CURSOR TO RIGHT )

0X05       :        SHIFT DISPLAY RIGHT

0X07       :        SHIFT DISPLAY TO LEFT

0X08       :        DISPLAY OFF CURSOR OFF
0X0A      :        DISPLAY OFF CURSOR ON

0X0E       :        DISPLAY ON  CURSOR OFF

0X0F        :       DISPLAY   ON  CURSOR ON

0X28        :        4 BIT LCD

0X38        :         8 BIT LCD


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