4-bit Initialization

Initialization of LCD is completed only after the reset sequence and basic initialization commands. We have already discussed about the reset sequence of the lcd in the previous section. So lets look at the programming now...

Assembly Program
;In this whole 4-bit tutorial LCD is connected to
;my controller in following way...
;D4 - P3.0
;D5 - P3.1
;D6 - P3.2
;D7 - P3.3
;EN - P3.7
;RS - P3.5

	lcd_port equ P3         ;LCD connected to Port3
	en equ P3.7             ;Enable connected to P3.7
	rs equ P3.5             ;Register select to P3.5
	
lcd_reset:                  ;LCD reset sequence
	mov lcd_port, #0FFH
	mov delay,#20           ;20mS delay
	acall delayms
	mov lcd_port, #83H      ;Data = 30H, EN = 1, First Init
	mov lcd_port, #03H      ;Data = 30H, EN = 0
	mov delay,#15           ;Delay 15mS
	acall delayms
	mov lcd_port, #83H      ;Second Init, Data = 30H, EN = 1

	mov lcd_port, #03H      ;Data = 30H, EN = 0
	mov delay,#5            ;Delay 5mS
	acall delayms
	mov lcd_port, #83H      ;Third Init

	mov lcd_port, #03H
	mov delay,#5            ;Delay 5mS
	acall delayms
	mov lcd_port, #82H      ;Select Data width (20H for 4bit)

	mov lcd_port, #02H      ;Data = 20H, EN = 0
	mov delay,#5            ;Delay 5mS
	acall delayms
	ret


lcd_init:
	acall lcd_reset         ;Call LCD Reset sequence
	mov a,#28H              ;4-bit, 2 line, 5x7 dots

	acall lcd_cmd           ;Call LCD command
	mov a,#0CH              ;Display ON cursor OFF
	acall lcd_cmd           ;Call LCD command
	mov a,#06H              ;Set entry mode (Auto increment)

	acall lcd_cmd           ;Call LCD command
	mov a,#80H              ;Bring cursor to line 1
	acall lcd_cmd           ;Call LCD command
	ret

C Program
//The pins used are same as explained earlier
#define lcd_port    P3

//LCD Registers addresses
#define LCD_EN      0x80
#define LCD_RS      0x20

void lcd_reset()
{
	lcd_port = 0xFF;
	delayms(20);
	lcd_port = 0x03+LCD_EN;
	lcd_port = 0x03;
	delayms(10);
	lcd_port = 0x03+LCD_EN;
	lcd_port = 0x03;
	delayms(1);
	lcd_port = 0x03+LCD_EN;
	lcd_port = 0x03;
	delayms(1);
	lcd_port = 0x02+LCD_EN;
	lcd_port = 0x02;
	delayms(1);
}

void lcd_init ()
{
	lcd_reset();         // Call LCD reset
	lcd_cmd(0x28);       // 4-bit mode - 2 line - 5x7 font. 
	lcd_cmd(0x0C);       // Display no cursor - no blink.
	lcd_cmd(0x06);       // Automatic Increment - No Display shift.
	lcd_cmd(0x80);       // Address DDRAM with 0 offset 80h.
 }

Sending Dommand/Data to LCD in 4-bit mode

Assembly Program
lcd_cmd:                  ;LCD command Routine
	mov temp,a            ;Save a copy of command to temp
	swap a                ;Swap to use higher nibble
	anl a,#0FH            ;Mask the first four bits
	add a,#80H            ;Enable = 1, RS = 0
	mov lcd_port,a        ;Move it to lcd port
	anl a,#0FH            ;Enable = 0, RS = 0
	mov lcd_port,a        ;Move to lcd port

	mov a,temp            ;Reload the command from temp
	anl a,#0FH            ;Mask first four bits
	add a,#80H            ;Enable = 1
	mov lcd_port,a        ;Move to port
	anl a,#0FH            ;Enable = 0
	mov lcd_port,a        ;Move to lcd port

	mov delay,#1          ;delay 1 ms
	acall delayms
	ret

lcd_dat:                  ;LCD data Routine
	mov temp,a            ;Keep copy of data in temp
	swap a                ;We need higher nibble
	anl a,#0FH            ;Mask first four bits
	add a,#0A0H           ;Enable = 1, RS = 1
	mov lcd_port,a        ;Move to lcd port
	nop
	clr en                ;Enable = 0

	mov a,temp            ;Reload the data from temp
	anl a,#0FH            ;we need lower nibble now
	add a,#0A0H           ;Enable = 1, RS = 1
	mov lcd_port,a        ;Move to lcd port
	nop
	clr en                ;Enable = 0

	mov delay,#1          ;Delay 1mS
	acall delayms
	ret

C Program
void lcd_cmd (char cmd)
{ 
	lcd_port = ((cmd >
>
 4) & 0x0F)|LCD_EN;
	lcd_port = ((cmd >
>
 4) & 0x0F);

	lcd_port = (cmd & 0x0F)|LCD_EN;
	lcd_port = (cmd & 0x0F);

	delayus(200);
	delayus(200);
}

void lcd_data (unsigned char dat)
{ 
	lcd_port = (((dat >
>
 4) & 0x0F)|LCD_EN|LCD_RS);
	lcd_port = (((dat >
>
 4) & 0x0F)|LCD_RS);
	
	lcd_port = ((dat & 0x0F)|LCD_EN|LCD_RS);
	lcd_port = ((dat & 0x0F)|LCD_RS);

	delayus(200);
	delayus(200);
}

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Conversation

Fri Sep 30 2016, 10:40 AM
Shahista
plz I want code for adc interfacing with8051
Sun Sep 25 2016, 04:41 AM
mira
hi sir, could you help me regarding simple multiplication calculator?it should be include with buzzer. i use dragonplus. please
ExperimenterUK
Sat Sep 24 2016, 05:49 PM
@Rus Ans .. what project ?
ExperimenterUK
Sat Sep 24 2016, 05:48 PM
@engr1931 depends on type of scanner
engr1931
Sat Sep 24 2016, 03:07 PM
Is it possible to send data from 2 barcode scanner to pc using serial port using 8051?
Wed Sep 21 2016, 02:22 AM
Rus Ana
can anyone help me for my project? T.T
Fri Sep 09 2016, 02:54 PM
Sarath babu
8051 a/c motor speed control
Tue Aug 30 2016, 05:03 PM
Kinzang
hello sir, can i know more in detail about the football substitution board project.
Tue Aug 30 2016, 06:06 AM
bhagyashri buddhewad
my project is automatic room light controller using visitor counter so i want coding in keil and circuit diagram can tell me and i want to use uc at89c51 thanks you
ExperimenterUK
Sun Aug 28 2016, 08:32 PM
Which project ?

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Wotszat
Thu Sep 29 2016, 06:31 AM
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CASINODIGITAL
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martinsnc115877 Avatar
Posted By martinsnc115877
Wed Sep 14 2016, 12:51 PM
sir, i did your led scrolling mass display, and it...
ExperimenterUK Avatar
Posted By ExperimenterUK
Fri Sep 09 2016, 11:45 PM
The Hex file for this project is a bit too big for...
rajavarmanslr Avatar
Posted By rajavarmanslr
Thu Aug 18 2016, 01:40 PM
I have two 8051 that interfaces with nRF24l01. One...
rajavarmanslr Avatar
Posted By rajavarmanslr
Thu Aug 18 2016, 12:31 PM
I have two 8051 that interfaces with nRF24l01. One...
ExperimenterUK Avatar
Posted By ExperimenterUK
Mon Aug 01 2016, 05:26 AM
is working nowugoo5000Great, thanks for letting u...
ugoo5000 Avatar
Posted By ugoo5000
Sat Jul 30 2016, 07:31 AM
is working noworg 00hmov p1,#11111111bmov p3,#1111...
ugoo5000 Avatar
Posted By ugoo5000
Sat Jul 30 2016, 06:40 AM
when i press a button in p3.0,the counter will st...
ugoo5000 Avatar
Posted By ugoo5000
Sat Jul 30 2016, 06:30 AM
proteus file Attachment ...
ExperimenterUK Avatar
Posted By ExperimenterUK
Fri Jul 29 2016, 11:34 PM
Your code does not count at all, it produces a one...
ugoo5000 Avatar
Posted By ugoo5000
Fri Jul 29 2016, 07:49 PM
i want the the counter to be counting in secs with...