[AVR] Please help me with checking the busy flag of an lcd in 4 bit mode

[aakashjsr]

I am able to execute commands on my lcd when I use delay instead of checking the busy flag but when I check the busy flag,it appears as if an infinite loop has started.Here's the connections for my 4 bit Lcd with the AVR Atmega 16.Thanks a lot in advance

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Code C - [expand]
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*****************************************************************************
PB0-> RS ; PB1->ENABLE ; PB2->R/W ; PB3->NOT CONNECTED
PB4-PB7----->DB4-DB7
 
*****************************************************************************                                                           Code:
*****************************************************************************
 
#define data PORTB
#define e PB1
#define rs PB0
#define rw PB2
 
void lcd_ready()  //checks for busy flag
{
 
    DDRB&=0b00001111;    //data lines as read
    int flag=0;
 
    cbi(PORTB,rs);
    sbi(PORTB,rw);
 
    do
    {
    pos_pulse();
    _delay_us(10);
    flag=PINB;
    flag=(flag&0x80); //to store the value of busy flag
    pos_pulse(); //discard lower nibble
    _delay_us(10);
    }while(flag);
    DDRB=0xff; //resetting data lines as output
}
 
void pos_pulse()
{   
    cbi(PORTB,e); // eable=0
    _delay_us(2);
    sbi(PORTB,e) ;  // eable=1
    _delay_us(2);
}
 
void neg_pulse()
{
    sbi(PORTB,e); // eable=1
    _delay_us(2);
    cbi(PORTB,e) ; // eable=0
    _delay_us(2);
}
 
void command(int a) // to receive and send command to LCD
{
 
//higher nibble
 
lcd_ready();
 
data=(a&0xf0);
cbi(PORTB,rs); 
cbi(PORTB,rw);
neg_pulse();
 
//Lower Nibble
 
lcd_ready();
 
data=((a<<4)&0xf0);
cbi(PORTB,rs); 
cbi(PORTB,rw);
neg_pulse();
}
 
 
 
void value(int a) //To send Data to the Lcd
{
 
//higher nibble
 
lcd_ready();
 
data=(a&0xf0);
sbi(PORTB,rs); 
cbi(PORTB,rw);
neg_pulse();
 
//Lower Nibble
 
lcd_ready();
 
data=((a<<4)&0xf0);
sbi(PORTB,rs); 
cbi(PORTB,rw);
neg_pulse();
 
 
}

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