| ??? 01/10/07 02:00 Read: times |
#130547 - Asm code Responding to: ???'s previous message |
Why does the assembler code have to be specific for the 2051/4051? Most people interface LCDs through the ports pins, so example code for any of the other 8051 variants are probably just as applicable. I would suggest you learn to read 'c' - its easier to read than assembler! Besides, you should be looking at the method rather than the actual code.
;----------------------------------------------------------------------------
;
;
; print messages on the lcd display.
; Dptr-> message in rom terminated by 00h
;
;
;----------------------------------------------------------------------------
pstring
clr a
movc a,@a+dptr
jz lcdp_2
lcall lcd_data_wr
inc dptr
sjmp pstring
lcdp_2
ret
;----------------------------------------------------------------------------
;
;
; Print hex value in A to the lcd display
;
;
;----------------------------------------------------------------------------
phex
push a
swap a
lcall hex
pop a
hex
anl a,#0fh
add a,#30h
cjne a,#3ah,hex_1
hex_1
jc hex_2
add a,#7
hex_2
lcall lcd_data_wr
ret
;----------------------------------------------------------------------------
;
;
; Print packed bcd value in A to the lcd display
;
;
;----------------------------------------------------------------------------
pbcd push a
swap a
anl a,#0fh
add a,#'0'
lcall lcd_data_wr
pop a
anl a,#0fh
add a,#'0'
ljmp lcd_data_wr
;----------------------------------------------------------------------------
;
;
; initialise the lcd display
;
;
;----------------------------------------------------------------------------
lcd_init
mov LCD_PORT,#0C0h
;
; delay 150mS
;
mov a,#150
lcall delay_1ms
mov a,#3
mov LCD_PORT,#0C3h
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay 50mS
;
mov a,#50
lcall delay_1ms
mov LCD_PORT,#0C3h
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay 50mS
;
mov a,#50
lcall delay_1ms
mov LCD_PORT,#0C3h
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay 10mS
;
mov a,#10
lcall delay_1ms
mov LCD_PORT,#0C2h
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay 10mS
;
mov a,#10 ; 10 * 100uS =1mS
lcall delay_1ms
mov a,#2ch ; 2 line mode
lcall lcd_comm_wr ; write lcd command
;
; delay 1mS
;
mov a,#100 ; 10 * 100uS =1mS
lcall delay_100u
mov a,#0ch ; display on,cursor off
lcall lcd_comm_wr ; write lcd command
;
; delay 1mS
;
mov a,#10 ; 10 * 100uS =1mS
lcall delay_100u
mov a,#06h ; auto inc,shift right
lcall lcd_comm_wr ; write lcd command
mov a,#01h
lcall lcd_comm_wr ; clear the display
;
; delay 10mS
;
mov a,#1
lcall delay_1ms
ret
;----------------------------------------------------------------------------
;
; Locate the lcd cursor. lcd_comm_wr routine must follow below!
; Cursor position in A
; zaps: A,B
;
;
;----------------------------------------------------------------------------
locate_cursor
cjne a,#16,lc_1
lc_1
jc lc_2 ; if location < 16 (line #1)
add a,#30h ; else add offset for 2nd line
lc_2
setb a.7 ; set bit 7 for locate cursor cmd
;----------------------------------------------------------------------------
;
;
; send a command to the lcd display. command in A
; Zaps: A,B
;
;----------------------------------------------------------------------------
lcd_comm_wr
clr LCD_RS
mov b,a ;save the command
swap a ;get hi nibble into low nibble
anl a,#0fh
mov c,a.0
mov P0.0,c
mov c,a.1
mov P0.1,c
mov c,a.2
mov P0.2,c
mov c,a.3
mov P0.3,c
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
mov a,b
anl a,#0fh
mov c,a.0
mov P0.0,c
mov c,a.1
mov P0.1,c
mov c,a.2
mov P0.2,c
mov c,a.3
mov P0.3,c
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay for lcd controller
;
mov b,#25 ;at least 40uS
ldrw_1
djnz b,ldrw_1 ;waste some time
ret
;******************************************************************************
;
;
; send data to the lcd display. command in A
; zaps: A,B
;
;
;******************************************************************************
lcd_data_wr
mov b,a ;save the command
swap a ;get hi nibble into low nibble
anl a,#0fh
mov c,a.0
mov P0.0,c
mov c,a.1
mov P0.1,c
mov c,a.2
mov P0.2,c
mov c,a.3
mov P0.3,c
setb LCD_RS
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
mov a,b
anl a,#0fh
mov c,a.0
mov P0.0,c
mov c,a.1
mov P0.1,c
mov c,a.2
mov P0.2,c
mov c,a.3
mov P0.3,c
setb LCD_RS
nop
nop
setb LCD_DEN
nop
nop
clr LCD_DEN
;
; delay for lcd controller
;
mov b,#25 ;at least 40uS
ldrw_2
djnz b,ldrw_2 ;waste some time
ret
;----------------------------------------------------------------------------
;
;
; Delay routine. A has # of 100 microseconds to delay
; zaps: A,B
;
;
;----------------------------------------------------------------------------
delay_100u
mov b,#54 ;@12.xxx mhz approx!
dly_1
djnz b,dly_1
djnz a,delay_100u
ret
;----------------------------------------------------------------------------
;
;
; Delay routine. A has # of 1 milliseconds to delay
; zaps: A,B
;
;
;----------------------------------------------------------------------------
delay_1ms
mov b,#120 ;@12.xxx mhz approx!
dly_2
nop
nop
nop
nop
nop
nop
djnz b,dly_2
djnz a,delay_1ms
ret
The lcd was connected to port0 in this instance lcd d4..7 to P0.0..3 lcd EN to P0.5 lcd RS to P0.4 lcd R/W to 0v This uses 4 bit mode - with is advisable due to the number of available port pins on a 2051/4051 Any questions :- refer to the hitachi hd44780 datasheet first. |
