AVR Freaks

hello  

i want to command an I/O expander PCF8574 with atmega382p but i don't get a result i'm using Microchip studio . this is my code: 

/// twi_lib.h
/*
 * twi_lib.h
 *
 * Created: 09/01/2022 5:25:27 PM
 *  Author: User
 */ 


#ifndef TWI_LIB_H_
#define TWI_LIB_H_


#define SCL_CLOCK  100000L


void twi_init();
uint8_t twi_start(char);
void twi_write(char);
char twi_read_ack();
char twi_read_nack();
void twi_stop();




#endif /* TWI_LIB_H_ */

//// twi_lib.c
/*
 * twi_lib.c
 *
 * Created: 09/01/2022 5:22:43 PM
 *  Author: User
 */ 

#include <compat/twi.h>
#include <util/delay.h>
#include "twi_lib.h"


void twi_init()
{
	TWSR = 0;
	TWBR = (((F_CPU/SCL_CLOCK)-16)/2) & 0xff;
}

uint8_t twi_start(char write_address)
{
	uint8_t   twst;
	// send start condition
	TWCR = (1<<TWEN)|(1<<TWSTA)|(1<<TWINT);	
	// wait until transmission completed
	while(!(TWCR & (1<<TWINT)));
	twst = TWSR;
	if (twst==0x08)
	{
		return 1;
	}
	// send device address
	TWDR = write_address;
	
	TWCR = (1<<TWINT) | (1<<TWEN);

	// wail until transmission completed and ACK/NACK has been received
	while(!(TWCR & (1<<TWINT)));
	
	// check value of TWI Status Register. Mask prescaler bits.
	twst = TW_STATUS & 0xF8;
	
	if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
	

	return 0;
	
}
void twi_write(char data)
{
		//uint8_t   twst;
		
		// send data to the previously addressed device
		//TWCR = (1<<TWINT) | (1<<TWEN);
		TWCR = 1<<TWINT;
		TWDR = data;
		TWCR = (1<<TWINT) | (1<<TWEN);

		// wait until transmission completed
		while(!(TWCR & (1<<TWINT)));
}
char twi_read_ack()
{
	TWCR = (1<<TWINT) | (1<<TWEN) ;
	while(!(TWCR & (1<<TWINT)));
	
	return TWDR;
}
char twi_read_nack()
{
	TWCR = (1<<TWINT) | (1<<TWEN);
	while(!(TWCR & (1<<TWINT)));
	
	return TWDR;
}
void twi_stop()
{
	/* send stop condition */
	TWCR = (1<<TWINT) | (1<<TWSTO) | (1<<TWEN);
	
	// wait until stop condition is executed and bus released
	while(TWCR & (1<<TWSTO));
	
}

///// main.c
/*
 * carte_I2C_relais.c
 *
 * Created: 27/12/2021 5:38:56 PM
 * Author : User
 */ 

#include <avr/io.h>
#include <compat/twi.h>
//#include<TWI_lib.h>
#include <util/delay.h>
#include "twi_lib.h"
uint32_t CPU_FREQ = 16000000;
int main(void)
{            
			 twi_init();
			 
			twi_start(0x20);
			while (1)
			{
				twi_write(0x40);
				twi_read_ack();
				twi_write(0x01);
				
				twi_stop();
			}
			
			
			
	

}

please check my code. thanks