[SOLVED] LCD code explaination

[bikashh]

dear friends,
i've got a code for my 20 X 4 LCD for my project using LPC2368 microcontroller.and it is working fine but the below portion is not clear to me...please give some light on it..

code1:

//Initialization:
void LcdInit (void)
{
LCD_IO_init(); //pin configuration
DelayMs(15) ;
DelayMs(15) ;
DelayMs(15) ;
DelayMs(15) ;
LcdCmd1(0x03) ;
DelayMs(6) ;
DelayMs(6) ;
DelayMs(6) ;
DelayMs(6) ;
LcdCmd1(0x03) ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
LcdCmd1(0x03) ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
LcdCmd1(0x02) ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;

LcdCmd(0x28) ;
LcdCmd(0x08) ;
LcdCmd(0x0c) ;
LcdCmd(0x06) ;
ClearLine(1);
ClearLine(2);

}

code2://command
void LcdCmd1 (unsigned char cmd)
{
unsigned int temp ;
LCD_SET1 = temp = LCD_DATA & (cmd << 20) ;
LCD_CLR1 = (temp ^ LCD_DATA) | (LCD_RS | LCD_EN);

SmallDelay() ;
LCD_SET1 = LCD_EN ;
SmallDelay() ;
LCD_CLR1 = LCD_EN ;
SmallDelay() ;
}

void LcdCmd (unsigned char cmd)
{
LcdCmd1(cmd >> 4) ;
LcdCmd1(cmd) ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
Delay250() ;
}
queries:

code1:
LcdCmd1(0x03) ;
why 0x03?


code2:
what does the line means
LCD_CLR1 = (temp ^ LCD_DATA) | (LCD_RS | LCD_EN);


thanks in advance

 

[alexan_e]

This is the exclusive or operation,

0^0 = 0
0^1 = 1
1^0 = 1
1^1 = 0

the variables temp and LCD_DATA are exclusive ORed bit by bit (bit0 with bit0, bit1 with bit1 etc)
usually this kind of operation is used to invert one or more bits,
anything exclusive ORed with 1 is inverted (a 0 becomes 1, and 1 becomes 0)

Alex

 

[bikashh]

but why do i need to do XORed
i only need to set the RS and than make EN high and low right?

tanks for the reply

 

[alexan_e]

The initialization of the LCD uses specific commands depending on the operation you want,
these are described in the datasheet of the LCD (the most common is HD44780 https://www.sparkfun.com/datasheets/LCD/HD44780.pdf )

Alex

 

[bikashh]

but if you see the code

LcdCmd(0x06) is doing "Entry mode set"
likewise what 0x03 does i didn't get from the datasheet

thanks

 

[alexan_e]

You can check the initialization steps explained better in **broken link removed**

Alex

 

[bikashh]

thanks a lot