RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
GPIOB->MODER &= ~(3 << (8*2));
GPIOB->MODER |= 2 << (8*2);
GPIOB->MODER &= ~(3 << (9*2));
GPIOB->MODER |= 2 << (9*2);

GPIOB->OTYPER |= 1 << 8;
GPIOB->OTYPER |= 1 << 9;

GPIOB->OSPEEDR &= ~(3 << (8*2));
GPIOB->OSPEEDR |= 1 << (8*2);
GPIOB->OSPEEDR &= ~(3 << (9*2));
GPIOB->OSPEEDR |= 1 << (9*2);

GPIOB->PUPDR &= ~(3 << (8*2));
GPIOB->PUPDR &= ~(3 << (9*2));

GPIOB->AFR[1] &= ~(0xF << (0*4));
GPIOB->AFR[1] |= 4 << (0*4);
GPIOB->AFR[1] &= ~(0xF << (1*4));
GPIOB->AFR[1] |= 4 << (1*4);

RCC->APB1ENR |= RCC_APB1ENR_I2C1EN;
RCC->CFGR3 &= ~RCC_CFGR3_I2C1SW;
I2C1->TIMINGR = 0x0010020A;
//I2C1->TIMINGR = 0x50330309;
//I2C1->TIMINGR = 0xA061191F;
I2C1->CR1 = I2C_CR1_PE;

I2C1->CR2 |= (0x3C << 1);
I2C1->CR2 &= ~I2C_CR2_RD_WRN;
I2C1->CR2 |= (1 << 16);
while(I2C1->ISR & I2C_ISR_BUSY);

I2C1->CR2 |= I2C_CR2_START;
//I2C1->CR2 |= I2C_CR2_AUTOEND;
//while(I2C1->CR2 & I2C_CR2_START);


while(!(I2C1->ISR & I2C_ISR_TXIS));
GPIOA->ODR |= BIT5;
I2C1->TXDR = 0xAE;
while(!(I2C1->ISR & I2C_ISR_TXE));

I2C1->CR2 |= I2C_CR2_STOP;
while(!(I2C1->ISR & I2C_ISR_STOPF));