LCD programming in PIC 18f4520...

[mohideen]

Hi all,
Does anyone have a simple example of a scrolling text for 2x16 LCD monitor, PIC18f program...
Thanks...

 

[chaudhryali55]

which compiler you are using ? and in which language you are using to code your lcd...?

 

[nikhil_jain]

if u re using mikroc, u can use

Lcd_Cmd(LCD_SHIFT_RIGHT);

or

Lcd_Cmd(LCD_SHIFT_LEFT);

within a loop to move ur text.

 

[chaudhryali55]

you can install mikro c pro compiler and you find many examples related to lcd scrolling...



feel free to ask anytime ....

 

[rabin2801]

if u re using mikroc, u can use or within a loop to move ur text.

Don't use pre defined library...
make ur own...
then u make all types of shifting also...
Example
/////////////////////////////////////////
//program specific declarations
sbit RS = P2^6; //P2^6 is connected to the RS line of LCD
sbit RW = P2^5; //P2^5 is connected to the RW line of LCD
sbit E = P2^4; //P2^4 is connected to the EN line of LCD
sbit BUSY = P2^3; //P2^3 is connected to the DB3 pin of LCD

unsigned char A=0; //variable used in the function swap(unsigned char tempdata)

// function for giving a delay of ms milliseconds
void delay_ms(unsigned int ms)
{
unsigned int i,j;

for(i=0;i<ms;i++)
for(j=0;j<53;j++);
}

void ready(void) // to check if LCD has finished executing previous command and is ready to accept next one
{
bit readybit;
unsigned char buzzer_status = 0;
buzzer_status = P2 & 0x80; //storing original buzzer status

E = 0;
RS = 0; // to select comand register
RW = 1; // to select read mode

while(readybit == 1) // keep checking MSB bit till busy goes low
{
E = 1; // high to low transition on E pin requird to clock in data
P2 = 0x7F | buzzer_status; // to set this pin in read mode to read busy signal from MSB
readybit = P2^3;
E = 0;
}
}

/************************************************************************

Function: swap(unsigned char tempdata)

Description: This function swaps the data which is passed to it
in such away that higher nibble is pushed in place of
lower nibble because lower nibble of Lcd is being used for data transfer.


************************************************************************/


unsigned char swap(unsigned char tempdata)
{
A = tempdata;
A = _cror_(A,4); // this uses an inbuilt rotate function to get MSB's in LSB's
tempdata = A & 0x0F;
return tempdata;
}


/*********************************************************

Function: commandsend(unsigned char command)

Description: This function sends data to LCD as command by
selecting the instruction register
**********************************************************/


void commandsend(unsigned char command)
{
unsigned char temp;
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

ready(); // checking for busy bit to send next nibble
temp = swap(command);
P2 = temp | buzzer_status; // to get higher nibble
RW = 0; // to select write mode
RS = 0; // to select command register
E = 1; // to get the enable high to low transition
E = 0; // in order to gate in the data


P2 = (command & 0x0F) | buzzer_status; // to get the lower nibble
RW = 0;
RS = 0; // repeat again all above steps

E = 1;
E = 0;
delay_ms(2); // delay of 2 ms
}


/*********************************************************

Function: datasend(unsigned char command)

Description: This function sends data to LCD as data by
selecting the data register
**********************************************************/
void datasend(unsigned char lcddata)
{
unsigned char temp;
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

temp = swap(lcddata);
ready(); // checkin gfor busy bit to send next nibble
P2 = temp | buzzer_status; // to get higher nibble
RW = 0; // to select write mode
RS = 1; // to select data register

E = 1;
E = 0;


P2 = (lcddata & 0x0F) | buzzer_status;
RW = 0;
RS = 1;
E = 1;
E = 0;
delay_ms(2); // delay of 2 ms
}

/***************************************************************************

Function: void lcdprint();

Description: This function converts digital data into ASCII and displays
sensor values on LCD display


***************************************************************************/

void lcdprint(unsigned char data_array[])
{
unsigned char data_array1[16]; //Array of 16 characters for Lcd line1
unsigned char data_array2[16]; //Array of 16 characters for Lcd line2
unsigned char temp=0;
unsigned char j=0;
unsigned char k=0;

for (j=0;j<8;j++)
{
temp=data_array[j];

if(k > 15)//if this condition is true loop arranges data for display onto the 2nd line
{
data_array2[k - 16] = (temp / 100) + 48; //Hundreds
data_array2[k - 15] = temp /10;
data_array2[k - 15] = (data_array2[k - 15] % 10) + 48; //Tens
data_array2[k - 14] = (temp % 10) + 48; //units
data_array2[k - 13] = ' ';
k = k + 4;
}
else //if the above condition is false loop arranges data for display onto the 1st line
{
data_array1[k] = (temp / 100) + 48; //Hundreds
data_array1[k + 1] = temp /10;
data_array1[k + 1]= (data_array1[k + 1] % 10) + 48; //Tens
data_array1[k + 2] = (temp % 10) + 48; //units
data_array1[k + 3] = ' ';
k = k + 4;
}
}

commandsend(0x80); //Set cursor position to first line first character
for (j=0;j<k;j++)//j keeps track of the cursor position on the LCD screen
{
if (j==16) //when j equals 16 it means cursor has to be shifted to 2nd line
commandsend (0xC0);//when end of 1st line is reached cursor is shifted to first position on 2nd line

if (j>15)//as long as j is greater than 15 it means that data has to be displayed on the 2nd line
datasend(data_array2[j-16]);//dispaly data onto 2nd line of LCD
else
datasend(data_array1[j]);//display data onto 1st line of LCD
}


commandsend (0x80);
}

/***********************************************************************
Function: lcd_init(void)
Description: This function initialises LCD display in 4-bit mode.
The intialisation functions are 8-bit wide, so we write
each inst into two seperate nibbles.
Following instructions are used for Lcd init.
1.> 0x30 8-bit mode
2.> 0x28 4-bit mode and 5x8 dot character font
3.> 0x0E Turn ON lcd and cursor
4.> 0x06 Autoincrement cursor position
5.> 0x01 Clear Lcd display
6.> 0x80 for setting cursor position
************************************************************************/

void lcd_init(void)
{
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

RS = 0; // to select comand register
RW = 0; // to select write mode
delay_ms(40); // on power ON we must allow a delay of 40ms for VCC to settle

E = 0;
P2 = 0x03 | buzzer_status; // send instruction to set FUNCTION SET to 8 bit mode though we have only connected 4 bit data bus because by default on power ON LCD is in 8 bit mode
E = 1;
E = 0;

delay_ms(4); // delay of 4ms

P2 = 0x03 | buzzer_status; // send the same instruction two times again. This way the LCD controller knows that we are operating in 4 bit mode
E = 1;
E = 0;
delay_ms(2); // delay of 2ms
P2 = 0x03 | buzzer_status;
E = 1;
E = 0;
delay_ms(2); // delay of 2ms

P2 = 0x02 | buzzer_status; // send FUNCTION SET instruction for 4 bit mode
E = 1;
E = 0;
ready();
P2 = 0x02 | buzzer_status; // again we send FUNCTION SET higher bits to keep 4 bit mode operation but main aim is to set the parameters in lower bits

E = 1;
E = 0;
P2 = 0x08 | buzzer_status; // these are the lower bits of FUNCTION SET. They set LCD to 1 display line and set font size to 5 x 8 dots

E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status; // higher bits of DISPLAY OFF instruction
E = 1;
E = 0;
P2 = 0x08 | buzzer_status; // lower bits of DISPLAY OFF instruction
E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status; // higher bits of CLEAR instruction
E = 1;
E = 0;
P2 = 0x01 | buzzer_status; // lower bits of CLEAR instruction
E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status;// higher bits of ENTRY MODE instruction
E = 1;
E = 0;

P2 = 0x06 | buzzer_status;// lower bits of ENTRY MODE instruction to set increment i.e display to right side mode and no shift
E = 1;
E = 0;
ready();

commandsend(0x0F); // set LCD ON; CURSOR OFF; BLINK ON.
commandsend(0x01); // clear display.
commandsend(0x06); // to set cursor auto increment
commandsend(0x80); //Set cursor position to first line first character
}

---------- Post added at 22:08 ---------- Previous post was at 22:07 ----------

if u re using mikroc, u can use or within a loop to move ur text.

Don't use pre defined library...
make ur own...
then u make all types of shifting also...
Example
/////////////////////////////////////////
//program specific declarations
sbit RS = P2^6; //P2^6 is connected to the RS line of LCD
sbit RW = P2^5; //P2^5 is connected to the RW line of LCD
sbit E = P2^4; //P2^4 is connected to the EN line of LCD
sbit BUSY = P2^3; //P2^3 is connected to the DB3 pin of LCD

unsigned char A=0; //variable used in the function swap(unsigned char tempdata)

// function for giving a delay of ms milliseconds
void delay_ms(unsigned int ms)
{
unsigned int i,j;

for(i=0;i<ms;i++)
for(j=0;j<53;j++);
}

void ready(void) // to check if LCD has finished executing previous command and is ready to accept next one
{
bit readybit;
unsigned char buzzer_status = 0;
buzzer_status = P2 & 0x80; //storing original buzzer status

E = 0;
RS = 0; // to select comand register
RW = 1; // to select read mode

while(readybit == 1) // keep checking MSB bit till busy goes low
{
E = 1; // high to low transition on E pin requird to clock in data
P2 = 0x7F | buzzer_status; // to set this pin in read mode to read busy signal from MSB
readybit = P2^3;
E = 0;
}
}

/************************************************************************

Function: swap(unsigned char tempdata)

Description: This function swaps the data which is passed to it
in such away that higher nibble is pushed in place of
lower nibble because lower nibble of Lcd is being used for data transfer.


************************************************************************/


unsigned char swap(unsigned char tempdata)
{
A = tempdata;
A = _cror_(A,4); // this uses an inbuilt rotate function to get MSB's in LSB's
tempdata = A & 0x0F;
return tempdata;
}


/*********************************************************

Function: commandsend(unsigned char command)

Description: This function sends data to LCD as command by
selecting the instruction register
**********************************************************/


void commandsend(unsigned char command)
{
unsigned char temp;
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

ready(); // checking for busy bit to send next nibble
temp = swap(command);
P2 = temp | buzzer_status; // to get higher nibble
RW = 0; // to select write mode
RS = 0; // to select command register
E = 1; // to get the enable high to low transition
E = 0; // in order to gate in the data


P2 = (command & 0x0F) | buzzer_status; // to get the lower nibble
RW = 0;
RS = 0; // repeat again all above steps

E = 1;
E = 0;
delay_ms(2); // delay of 2 ms
}


/*********************************************************

Function: datasend(unsigned char command)

Description: This function sends data to LCD as data by
selecting the data register
**********************************************************/
void datasend(unsigned char lcddata)
{
unsigned char temp;
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

temp = swap(lcddata);
ready(); // checkin gfor busy bit to send next nibble
P2 = temp | buzzer_status; // to get higher nibble
RW = 0; // to select write mode
RS = 1; // to select data register

E = 1;
E = 0;


P2 = (lcddata & 0x0F) | buzzer_status;
RW = 0;
RS = 1;
E = 1;
E = 0;
delay_ms(2); // delay of 2 ms
}

/***************************************************************************

Function: void lcdprint();

Description: This function converts digital data into ASCII and displays
sensor values on LCD display


***************************************************************************/

void lcdprint(unsigned char data_array[])
{
unsigned char data_array1[16]; //Array of 16 characters for Lcd line1
unsigned char data_array2[16]; //Array of 16 characters for Lcd line2
unsigned char temp=0;
unsigned char j=0;
unsigned char k=0;

for (j=0;j<8;j++)
{
temp=data_array[j];

if(k > 15)//if this condition is true loop arranges data for display onto the 2nd line
{
data_array2[k - 16] = (temp / 100) + 48; //Hundreds
data_array2[k - 15] = temp /10;
data_array2[k - 15] = (data_array2[k - 15] % 10) + 48; //Tens
data_array2[k - 14] = (temp % 10) + 48; //units
data_array2[k - 13] = ' ';
k = k + 4;
}
else //if the above condition is false loop arranges data for display onto the 1st line
{
data_array1[k] = (temp / 100) + 48; //Hundreds
data_array1[k + 1] = temp /10;
data_array1[k + 1]= (data_array1[k + 1] % 10) + 48; //Tens
data_array1[k + 2] = (temp % 10) + 48; //units
data_array1[k + 3] = ' ';
k = k + 4;
}
}

commandsend(0x80); //Set cursor position to first line first character
for (j=0;j<k;j++)//j keeps track of the cursor position on the LCD screen
{
if (j==16) //when j equals 16 it means cursor has to be shifted to 2nd line
commandsend (0xC0);//when end of 1st line is reached cursor is shifted to first position on 2nd line

if (j>15)//as long as j is greater than 15 it means that data has to be displayed on the 2nd line
datasend(data_array2[j-16]);//dispaly data onto 2nd line of LCD
else
datasend(data_array1[j]);//display data onto 1st line of LCD
}


commandsend (0x80);
}

/***********************************************************************
Function: lcd_init(void)
Description: This function initialises LCD display in 4-bit mode.
The intialisation functions are 8-bit wide, so we write
each inst into two seperate nibbles.
Following instructions are used for Lcd init.
1.> 0x30 8-bit mode
2.> 0x28 4-bit mode and 5x8 dot character font
3.> 0x0E Turn ON lcd and cursor
4.> 0x06 Autoincrement cursor position
5.> 0x01 Clear Lcd display
6.> 0x80 for setting cursor position
************************************************************************/

void lcd_init(void)
{
unsigned char buzzer_status = 0;

buzzer_status = P2 & 0x80; //storing original buzzer status

RS = 0; // to select comand register
RW = 0; // to select write mode
delay_ms(40); // on power ON we must allow a delay of 40ms for VCC to settle

E = 0;
P2 = 0x03 | buzzer_status; // send instruction to set FUNCTION SET to 8 bit mode though we have only connected 4 bit data bus because by default on power ON LCD is in 8 bit mode
E = 1;
E = 0;

delay_ms(4); // delay of 4ms

P2 = 0x03 | buzzer_status; // send the same instruction two times again. This way the LCD controller knows that we are operating in 4 bit mode
E = 1;
E = 0;
delay_ms(2); // delay of 2ms
P2 = 0x03 | buzzer_status;
E = 1;
E = 0;
delay_ms(2); // delay of 2ms

P2 = 0x02 | buzzer_status; // send FUNCTION SET instruction for 4 bit mode
E = 1;
E = 0;
ready();
P2 = 0x02 | buzzer_status; // again we send FUNCTION SET higher bits to keep 4 bit mode operation but main aim is to set the parameters in lower bits

E = 1;
E = 0;
P2 = 0x08 | buzzer_status; // these are the lower bits of FUNCTION SET. They set LCD to 1 display line and set font size to 5 x 8 dots

E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status; // higher bits of DISPLAY OFF instruction
E = 1;
E = 0;
P2 = 0x08 | buzzer_status; // lower bits of DISPLAY OFF instruction
E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status; // higher bits of CLEAR instruction
E = 1;
E = 0;
P2 = 0x01 | buzzer_status; // lower bits of CLEAR instruction
E = 1;
E = 0;
ready();
P2 = 0x00 | buzzer_status;// higher bits of ENTRY MODE instruction
E = 1;
E = 0;

P2 = 0x06 | buzzer_status;// lower bits of ENTRY MODE instruction to set increment i.e display to right side mode and no shift
E = 1;
E = 0;
ready();

commandsend(0x0F); // set LCD ON; CURSOR OFF; BLINK ON.
commandsend(0x01); // clear display.
commandsend(0x06); // to set cursor auto increment
commandsend(0x80); //Set cursor position to first line first character
}