Hello,
STM32F103RB microcontroller.
7-bit master transmitter (see Figure 273).
When I send Address then I receive AF bit of I2C_SR1 register equals "1" (Acknowledge failure). But the diagram taken from the oscilloscope shows that after the address there is a Acknowledge bit equal to "0". Which does not correspond to the AF bit in I2C_SR1 register. Why? I also attach the program code.
/**
* @brief This function must be called before using other functions from this file.
* None.
* @retval None.
*/
void init_i2c1(void)
{
RCC->APB2ENR |= 0x00000008;
RCC->APB1ENR |= 0x00200000;
GPIOB->CRL &= 0x44000000;
GPIOB->CRL |= 0xDD000000;
I2C1->CR2 |= 0x0008;
I2C1->CCR |= 0x0028;
I2C1->TRISE |= 0x0009;
I2C1->CR1 |= 0x0401;
}
/**
* @brief This function must be called to generate START condition.
* None.
* @retval Execution result code:
* - 0: Not successfully.
* - 1: Successfully.
*/
unsigned char start_i2c1(void)
{
unsigned int temp = 0;
I2C1->CR1 |= 0x0100;
/*while ((I2C1->SR1 & 0x0001) == 0x0000)
;*/
temp = 0;
while (temp <= 10000)
{
if ((I2C1->SR1 & 0x0001) == 0x0001)
{
return 0x01;
}
else
{
temp++;
}
}
return 0x00;
}
/**
* @brief This function must be called to send address byte.
* address: Slave device address.
* mode: Operation mode.
* - 0: Write.
* - 1: Read.
* @retval Execution result code:
* - 0: Not successfully.
* - 1: Successfully.
*/
unsigned char send_address_byte(unsigned char address, unsigned char mode)
{
unsigned int temp = 0;
if ((mode & 0x01) == 0x01)
{
address |= 0x01;
}
else
{
address &= ~0x01;
}
I2C1->DR = address;
temp = 0;
while (temp <= 10000)
{
if ((I2C1->SR1 & 0x0400) == 0x0400)
{
I2C1->SR1 &= ~0x0400;
I2C1->CR1 |= 0x0200;
return 0x00;
}
else
{
temp++;
}
}
I2C1->CR1 |= 0x0200;
return 0x01;
}
int main(void)
{
int temp = 0;
init_i2c1();
while(1)
{
if (start_i2c1() == 0x01)
{
if (send_address_byte(0x90, 0x00) == 0x01)
{
temp++;
}
else
{
temp++;
}
}
else
{
temp++;
}
}
}
I'm looking through the debugger.
This loop constantly returns 0x00 (see above is the full code).
while (temp <= 10000)
{
if ((I2C1->SR1 & 0x0400) == 0x0400)
{
I2C1->SR1 &= ~0x0400;
I2C1->CR1 |= 0x0200;
return 0x00;
}
else
{
temp++;
}
}
