Hi,

In 4 bit mode there should be two writes one for high nibble and other for lower niblle.

I have given a sample init LCD code for your understanding.

void init_LCD(void)
{

LCD_RW = 0 ;
delay(200); // Wait 20ms
LCD_E = 0;
LCD_RS = CTRL_REG; // Switch to inruction register

//Set LCD_DATA to high nibble of Software Reset
LCD_DATA = (LCD_DATA&0x0F)|0x30;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(50); // Wait 5ms

LCD_E = 1; LCD_E = 0; // Write data to display again (SW Reset)
delay(50); // Wait 5ms

LCD_E = 1; LCD_E = 0; // Write data to display again (SW Reset)
delay(50); // Wait 5ms

// Set LCD_DATA to high nibble of Function Set (4Bit)
LCD_DATA = (LCD_DATA&0x0F)|0x20;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(4);

// Set LCD_DATA to high nibble of Function Set : 4 bit, 2 lines, 5*7 font
LCD_DATA = (LCD_DATA&0x0F)|0x20;
LCD_E = 1; LCD_E = 0; // Write data to display
// Set LCD_DATA to lower nibble of Function Set : 4 bit, 2 lines, 5*7 font
LCD_DATA = (LCD_DATA&0x0F)|0x80;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(4); // Wait 400µs

// Set LCD_DATA to high nibble of Display On/Off Control : display off, cursor off, don´t blink
LCD_DATA = (LCD_DATA&0x0F)|0x00;
LCD_E = 1; LCD_E = 0; // Write data to display
// Set LCD_DATA to lower nibble of Display On/Off Control : display off, cursor off, don´t blink
LCD_DATA = (LCD_DATA&0x0F)|0x80;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(4); // Wait 400µs

// Set LCD_DATA to high nibble of Clear Display
LCD_DATA = (LCD_DATA&0x0F)|0x00;
LCD_E = 1; LCD_E = 0; // Write data to display
// Set LCD_DATA to lower nibble of Clear Display
LCD_DATA = (LCD_DATA&0x0F)|0x10;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(50); // Wait 5ms

// Set LCD_DATA to high nibble of Entry Mode Set : increment DD-RAM address, move cursor
LCD_DATA = (LCD_DATA&0x0F)|0x00;
LCD_E = 1; LCD_E = 0; // Write data to display
// Set LCD_DATA to lower nibble of Entry Mode Set : increment DD-RAM address, move cursor
LCD_DATA = (LCD_DATA&0x0F)|0x60;
LCD_E = 1; LCD_E = 0; // Write data to display
delay(4); // Wait 400µs

return;
}