Rami Alrz....

It will not be possible to give your more help unless you can take some of your valuable time to describe accurately how you have the LCD connected to the micro controller. When you take the time to do that please consider to present the information as also answering the following questions....

1) Does your processor have its board level interface setup with a standard external memory bus interface?

2) What is the CS2_ signal that you describe? Where does that come from?

3) Is the EN signal that you describe as "thro NOR gate" originate at the processor and go to the input of the gate OR does the gate produce this signal and drive it as the E signal to the LCD interface?

It seems to me that from what I can infer from your terse description of the LCD hookup that you appear to have it on an external bus and that the LCD is memory mapped into the external address space. Thus the following schematic may be close to what you are working with.



If this is the case then you will access the LCD controller via the MOVX instruction. In the above sample schematic the LCD controller is mapped to a series of addresses in the 02000H bank. Here is a truth table of the addresses...

            RS  RW
Address  -  A2  A1  A0   --  Function
-------------------------------------
 02000H      0   0   0       Write Command Register
 02001H      0   0   1         (same as above)
 02002H      0   1   0       Read Status Register
 02003H      0   1   1         (same as above)
 02004H      1   0   0       Write Data Register
 02005H      1   0   1         (same as above)
 02006H      1   1   0       Read Data Register
 02007H      1   1   1         (same as above)

Thus here are code sequences to access the ports:

-- Read Status Register (status into A)
   MOV   DPTR,#02002H
   MOVX  A,@DPTR

-- Write Command Register (command from A)
   MOV   DPTR,#02000H
   MOVX  @DPTR,A

-- Write Data Register (data from A)
   MOV   DPTR,#02004H
   MOVX  @DPTR,A

This should give you guidance.....particularly to the level of connection detail you will have to provide if your connection details are different than this schematic.

Michael Karas