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// Program for Master Mode

#include
#include
#include

void TWI_start(void);
void TWI_repeated_start(void);
void TWI_init_master(void);
void TWI_write_address(unsigned char);
void TWI_read_address(unsigned char);
void TWI_write_data(unsigned char);
void TWI_read_data(void);
void TWI_stop(void);

unsigned char address1=0×20,address2=0×08, read=1, write=0,address=0×20;unsigned char write_data=0xf0, recv_data;
int c=0;int dt=0,i=0;
int main(void)
{
_delay_ms(2000);

DDRA=0xff;

if(write_data==0×00)
write_data=0xf0;

TWI_init_master();
TWI_start();
TWI_write_address(address+write);
TWI_write_data(write_data);dt=1;
TWI_write_data(0x1f);dt=0;
PORTA=0xff;

address=0×08;
c=1;

TWI_repeated_start();
TWI_write_address(address+write);
TWI_write_data(write_data);dt=1;
TWI_write_data(0x1f);dt=0;
TWI_stop();

while(1)
{

}

}

void TWI_init_master(void) // Function to initialize master
{

TWBR=0×12; // Bit rate
TWSR=(0<<TWPS1)|(1<<TWPS0); // Setting prescalar bits
// SCL freq= F_CPU/(16+2(TWBR).4^TWPS)
}

void TWI_start(void)
{
// Clear TWI interrupt flag, Put start condition on SDA, //Enable TWI
TWCR= (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);

// Wait till start condition is transmitted
while(!(TWCR & (1<<TWINT)));

// Check for the acknowledgement
while((TWSR & 0xF8)!= 0×08);
}

void TWI_repeated_start(void)
{
//Clear TWI interrupt flag, Put start condition on SDA, //Enable TWI
TWCR= (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);

// wait till restart condition is transmitted
while(!(TWCR & (1<<TWINT)));

// Check for the acknoledgement
while((TWSR & 0xF8)!= 0×10);
}

void TWI_write_address(unsigned char data)
{
TWDR=data; // Address and write instruction
// Clear TWI interrupt flag,Enable TWI
TWCR=(1<<TWINT)|(1<<TWEN);

// Wait till complete TWDR byte transmitted
while (!(TWCR & (1<<TWINT)));

// Check for the acknoledgement
while((TWSR & 0xF8)!= 0×18);
}

void TWI_read_address(unsigned char data)
{
TWDR=data; // Address and read instruction
// Clear TWI interrupt flag,Enable TWI
TWCR=(1<<TWINT)|(1<<TWEN);

// Wait till complete TWDR byte received
while (!(TWCR & (1<<TWINT)));

// Check for the acknoledgement
while((TWSR & 0xF8)!= 0×40);
}

void TWI_write_data(unsigned char data)
{
TWDR=data; // put data in TWDR
// Clear TWI interrupt flag,Enable TWI
TWCR=(1<<TWINT)|(1<<TWEN);
// Wait till complete TWDR byte transmitted
while (!(TWCR & (1<<TWINT)));

// Check for the acknoledgement
while((TWSR & 0xF8) != 0×28);
}

void TWI_read_data(void)
{
// Clear TWI interrupt flag,Enable TWI
TWCR=(1<<TWINT)|(1<<TWEN);

// Wait till complete TWDR byte transmitted
while (!(TWCR & (1<<TWINT)));

// Check for the acknoledgement
while((TWSR & 0xF8) != 0×58);

recv_data=TWDR;
PORTA=recv_data;
}

void TWI_stop(void)
{
// Clear TWI interrupt flag, Put stop condition on SDA, //Enable TWI
TWCR= (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);
// Wait till stop condition is transmitted
while(!(TWCR & (1<<TWSTO)));

}

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