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Ömer Faruk
Joined: 15 Nov 2018
Posts: 42
Location: Çanakkale
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| Shift left or right in serial lcd |
 Posted: Thu Nov 22, 2018 12:52 pm |
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Hello everyone
İ got this i2c serial lcd code in ccs c forum. İt works well but i couldn't find out how to shift the lcd right or left. Please help me.
| Code: |
//-----------------------------------------------------------------------------
// Title: i2c_Flex_LCD
// Description: Driver for common LCD with 1/2/3 or 4 row modules using PCF8574T interface board with I2C protocol.
// Date: Nov-2013
// Ver.Rev.: 1.0
// Author: Hugo Silva (sergio-hugo@bol.com.br) #Based on the routines of 20X4_LCD_I2C_DRIVER.h from Pumrin S.
//-----------------------------------------------------------------------------
//
// lcd_init() Must be called before any other function.
//
// lcd_putc(c) Will display c on the next position of the LCD.
//
// \f Clear LCD dispay
// \1 Set write position on LCD Line 1
// \2 Set write position on LCD Line 2
// \3 Set write position on LCD Line 3
// \4 Set write position on LCD Line 4
//
// lcd_gotoxy(x,y) Set write position on LCD (upper left is 1,1)
//
//-----------------------------------------------------------------------------
// LCD pins D0-D3 are not used.
//-----------------------------------------------------------------------------
//
// Commment : Control of a compatible LCD HITACHI from a bus I2C with
// an EXPANDER of I/O with connection I2C. The tests of these
// routines have been programmed using the IC PCF8574T of Phillips.
// I used 4 bits mode programming. The 8 bits mode programming
// is possible if you use 2 x PCF8574T.
//
// As defined in the following structure the pin connection is as follows:
//
// PCF8574P LCD
// ======== ======
// P0 RS
// P1 RW
// P2 Enable
// P3 Led Backlight
// P4 D4
// P5 D5
// P6 D6
// P7 D7
//
// The SCL and SDA pins should be pull-up resistor as shown below:
//
// +5v
// |
// <
// > 4.7K
// <
//To PIC | To i2c slave
//pin xx ------------------ SDA pin
//(SDA)
// +5v
// |
// <
// > 4.7K
// <
//To PIC | To i2c slave
//pin xx ------------------ SCL pin
//(SCL)
//
//To PIC To i2c slave
//Vss pin ----------------- Vss or ground pin
// |
// -----
// --- Ground
// -
//
// THIS DOCUMENT IS PROVIDED TO THE USER "AS IS"
//-----------------------------------------------------------------------------
#define LCD_ADDR 0x4E //I2C slave address for LCD module
#define ON 1
#define OFF 0
#define RS 0b00000001 //P0 - PCF8574T Pin connected to RS
#define RW 0b00000010 //P1 - PCF8574T Pin connected to RW
#define EN 0b00000100 //P2 - PCF8574T Pin connected to EN
#define BACKLIGHT_LED 0b00001000 //P3 - PCF8574T Pin connected to BACKLIGHT LED
#define lcd_line_one 0x80 // LCD RAM address for line 1
#define lcd_line_two 0xC0 // LCD RAM address for line 2
#define lcd_line_three 0x94 // LCD RAM address for line 3
#define lcd_line_four 0xD4 // LCD RAM address for line 4
byte address;
int1 lcd_backlight=ON;
void i2c_send_nibble(unsigned char data)
{
i2c_start();
delay_us(20);
i2c_write(LCD_ADDR); //the slave addresse
delay_us(20);
i2c_write(data);
delay_us(20);
i2c_stop();
delay_us(20);
}
void lcd_send_byte(unsigned char data)
{
if (lcd_backlight) data=data|EN|BACKLIGHT_LED; else data=data|EN; //set pin EN
i2c_send_nibble(data);
data=data-4; //toggle EN back to 0
i2c_send_nibble(data);
}
void lcd_clear()
{
lcd_send_byte(0x00);
lcd_send_byte(0x10);
delay_ms(2);
}
void lcd_init()
{
delay_ms(200); //LCD power up delay
//Request works on the command by set the RS = 0 R/W = 0 write
lcd_send_byte(0x00);
lcd_send_byte(0x10);
lcd_send_byte(0x00);
lcd_send_byte(0x00);
lcd_send_byte(0x10);
//First state in 8 bit mode
lcd_send_byte(0x30);
lcd_send_byte(0x30);
//Then set to 4-bit mode
lcd_send_byte(0x30);
lcd_send_byte(0x20);
//mode 4 bits, 2 lines, characters 5 x 7 (28 h)
lcd_send_byte(0x20);
lcd_send_byte(0x80);
//no need cursor on (0Ch)
lcd_send_byte(0x00);
lcd_send_byte(0xC0);
//the cursor moves to the left (06 h)
lcd_send_byte(0x00);
lcd_send_byte(0x60);
//clears the display
lcd_clear();
}
void lcd_gotoxy( byte x, byte y)
{
static char data;
switch(y)
{
case 1: address= lcd_line_one; break;
case 2: address= lcd_line_two; break;
case 3: address= lcd_line_three; break;
case 4: address= lcd_line_four; break;
default: address= lcd_line_one; break;
}
address+=x-1;
data=address&0xF0;
lcd_send_byte(data);
data=address&0x0F;
data=data<<4;
lcd_send_byte(data);
}
//Display the character on LCD screen.
void LCD_PUTC(char in_data)
{
char data;
switch(in_data)
{
case '\f': lcd_clear() ; break;
case '\1': lcd_gotoxy(1,1); break;
case '\2': lcd_gotoxy(1,2); break;
case '\3': lcd_gotoxy(1,3); break;
case '\4': lcd_gotoxy(1,4); break;
default:
data=in_data&0xF0;
data=data|RS; //set RS pin to 1
lcd_send_byte(data);
data=in_data&0x0F;
data=data<<4;
data=data|RS; //set RS pin to 1
lcd_send_byte(data);
break;
}
} |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19513
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| Posted: Thu Nov 22, 2018 1:37 pm |
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| You don't. You just have a string, and rotate this, then draw this back to the display. |
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temtronic
Joined: 01 Jul 2010
Posts: 9226
Location: Greensville,Ontario
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| Posted: Thu Nov 22, 2018 2:48 pm |
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| Some LCD modules may have a command to shift the data, though you'll have to read the specific datasheet for YOUR LCD module. On the ones I use( a 20 x 4 unit) there's a command called 'Display Shift' , that will shift either the data or the cursor, left or right. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19513
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| Posted: Thu Nov 22, 2018 2:53 pm |
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Yes. However there is then the need to rewrite the driver code to deal with
the shifted display. Ones that allow you to shift the data origin, result in
subsequent data writes not going to the right location.... 
There are a few that allow shifting without moving the data origin, but
these are relatively rare.
Generally far easier to just rewrite the shifted data. |
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