Dear All,

In Tutorial: Introduction to LCD Programming 2: Driving 4-bit Mode
<pre>http://www.8052.com/tutlcd2.phtml

There are errors in the mentioned data like that:-

WRITE_2_NIBBLES:

PUSH ACC ;Save A for low nibble
ORL DATA,#0F0h ;Bits 4..7 <- 1
ORL A,#0F0h ;Don't affect bits 0-3
ANL DATA,A ;High nibble to display
SETB EN
CLR EN
POP ACC ;Prepare to send
SWAP A ;...second nibble
ORL DATA,#0F0h ; Bits 4...7 <- 1
ORL A,#0F0h ; Don't affect bits 0...3
ANL DATA,A ;Low nibble to display
SETB EN
CLR EN
RET

Should be like that:-

WRITE_2_NIBBLES:

PUSH ACC ;Save A for low nibble
ORL DATA,#0F0h ;Bits 4..7 <- 1
ORL A,#0Fh ;Don't affect bits 4...7
ANL DATA,A ;High nibble to display
SETB EN
CLR EN
POP ACC ;Prepare to send
SWAP A ;...second nibble
ORL DATA,#0F0h ; Bits 4...7 <- 1
ORL A,#0Fh ; Don't affect bits 4...7
ANL DATA,A ;Low nibble to display
SETB EN
CLR EN
RET