[STM32F107]I2C problem

[żabek]

Hello

I'm facing a strange problem and I cannot find a solution myself, I'm simply stuck.
I'm trying to interface STM32F107 microcontroller with (among others) 2 PCF8574 I2C bus expanders. Hardware seems to be OK, verified with oscilloscope, seems correct. Unfortunately neither of PCFs change output states as desired. Below I attach my code, maybe there's something that causes malfunction and I cannot see it.
I don't want to use ST's library. Code isn't interrupt driven.

void I2CInit(void)
{
	RCC->APB1ENR |= RCC_APB1Periph_I2C1;										//wlacz zegar dla I2C1
	GPIOB->CRH |= 0x00000000;
	GPIOB->CRL |= 0xFF000000;
	I2C1->CR2 |= 0x36;																			//36MHz
	I2C1->TRISE = 0x26;																			//1us
	I2C1->CCR = 0xB4;               												//100kHz
	I2C1->CR1 = 0x01;																				//wlacz I2C
}

void I2CStart(void)
{
	uint16_t dummy;
	while((((I2C1->SR2) >> 1)&0x01)!=0x00);									//czekaj poki BUSY
	I2C1->CR1 |= (uint16_t)(0x01 << 8);
	while((((I2C1->SR1) >> 0)&0x01)!=0x01);									//czekaj az ustawi sie flaga SB
	dummy = I2C1->SR1;
	dummy = I2C1->SR2;																			//skasuj ewentualne flagi
}

void I2CAddr(uint8_t address)
{
	uint16_t dummy;
	I2C1->DR = address;
																				
	while((((I2C1->SR1) >> 1)&0x01)!=0x00);									//czekaj az wyzeruje sie flaga ADDR
	dummy = I2C1->SR1;	
	dummy = I2C1->SR2;																			//skasuj ewentualne flagi
																					
}

void I2CSend(uint8_t data)
{
	uint16_t dummy;
	I2C1->DR = data;
	while((((I2C1->SR1) >> 7)&0x01)!=0x01);
	dummy = I2C1->SR1;
	dummy = I2C1->SR2;																			//skasuj ewentualne flagi
}

uint8_t I2CRead(uint8_t ack)
{
	uint16_t dummy;
	if(ack)
		I2C1->CR1 |= (uint16_t)(0x01 << 10);
	else
		I2C1->CR1 &= ~((uint16_t)(0x01 << 10));
	while((((I2C1->SR1) >> 6)&0x01)!=0x00);
	dummy = I2C1->SR1;
	dummy = I2C1->SR2;																			//skasuj ewentualne flagi
	return((uint8_t)(I2C1->DR));
}

void I2CStop(void)
{
	uint16_t dummy;
	I2C1->CR1 |= (uint16_t)(0x01 << 9);
	dummy = I2C1->SR1;
	dummy = I2C1->SR2;																			//skasuj ewentualne flagi
}

Sorry for comments in Polish ;-)

Below how the transmission is called from main function

	I2CStart();
	I2CAddr(0x70|WRITE);												//IC16
	I2CSend(0xAA);
	I2CStop();	
	
	I2CStart();
	I2CAddr(0x7E|WRITE);												//IC17
	I2CSend(0x55);
	I2CStop();

Addresses are OK, chips send ACKs when they're supposed to but do not change output states. Sometimes I succeed when I'm performing step-by-step debugging...
Could anyone have a look and help me find a solution, please?

BRegards
Damian

 

[żabek]

Hey Guys,

It's my second threat on EDA board and second with no response... Are my questions really so difficult or is it a forum for beginners only and hard cases are forbidden here?