Quote from lvivgeorge on November 5, 2024, 8:20 pm

Please help me understand what I'm doing wrong here.

I've tested with a real Arduino UNO (compiled using raw AVR) and a PCF8574 (as module for LCD1602, and simply connected to P0, P1 and P2), and everything works perfectly.

I want to reproduce same example in Simulide, but it's not working, I made next circuit, changed I2C address to 63 in I2C expander, but nothing happens

 

My code

#include <avr/io.h>

#include <util/delay.h>

#include <avr/interrupt.h>

#define F_CPU 16000000UL // CPU frequency

#define PCF8574_ADDRESS 0x3F

void i2cInit();

void i2cStart();

void i2cStop();

void i2cWrite(uint8_t data);

void PCF8574_write(uint8_t data) {

i2cStart();

i2cWrite(PCF8574_ADDRESS<<1); // Left-shift to add write bit

i2cWrite(data); // Send data to PCF8574

i2cStop();

}

int main(void) {

i2cInit();

while (1) {

PCF8574_write(0x00);

_delay_ms(500);

PCF8574_write(0xFF);

_delay_ms(500);

}

return0;

}

void i2cInit() {

TWSR=0x00; // Set prescaler to 1

TWBR=0x48; // 100kHz SCL frequency for F_CPU = 16MHz

TWCR= (1<<TWEN); // Enable TWI

}

void i2cStart() {

TWCR= (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); // Send start condition

while (!(TWCR& (1<<TWINT))); // Wait for TWINT flag

_delay_us(10);

}

void i2cStop() {

TWCR= (1<<TWINT) | (1<<TWSTO) | (1<<TWEN); // Send stop condition

_delay_us(10);

}

void i2cWrite(uint8_t data) {

TWDR=data;

TWCR= (1<<TWINT) | (1<<TWEN); // Start transmission

while (!(TWCR& (1<<TWINT))); // Wait for TWINT flag

}