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STM32 + I2C

Question asked by framiche on Dec 4, 2012
Latest reply on Dec 4, 2012 by fm
Hi all,
     I am using STm32f2 series and I have a sensor on I2C bus. The problem is that my I2C bus is always busy.
My code:
void setupClock()
      RCC_DeInit ();                    
      RCC_HSEConfig (RCC_HSE_ON);   
      while (RCC_GetFlagStatus(RCC_FLAG_HSERDY) == RESET);
      RCC_HCLKConfig   (RCC_SYSCLK_Div1); 
      RCC_PCLK2Config  (RCC_HCLK_Div1); 
      RCC_PCLK1Config  (RCC_HCLK_Div2);
      RCC_ADCCLKConfig (RCC_PCLK2_Div4);
      RCC_PLLConfig (0x00010000, RCC_PLLMul_9);
      RCC_PLLCmd (ENABLE);
      while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
      while (RCC_GetSYSCLKSource() != 0x08);
void setupI2C2()
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C2, ENABLE);
    RCC_APB2PeriphClockCmd (RCC_APB2Periph_GPIOB, ENABLE);

    GPIO_InitTypeDef  GPIO_InitStructure;
    I2C_InitTypeDef  I2C_InitStructure;

    GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_10 | GPIO_Pin_11;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
    I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
    I2C_InitStructure.I2C_OwnAddress1 = I2C_SLAVE_ADDRESS7;
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2C_InitStructure.I2C_ClockSpeed = I2C2_SPEED;
    I2C_Init(I2C2, &I2C_InitStructure);
    I2C_Cmd(I2C2, ENABLE);

In main(void) I call setupClock() and setupI2C2() functions. If i check I2C_GetFlagStatus(I2C2, I2C_FLAG_BUSY) this flag is always true!
If I configure SDA and SCL as GPIO, I see that at the begin SDA is down. So I manually generate a square-wave on SCL pin until SDA is down. In this way SDA return up but the problem remains.

Any help in resolving the issue will be appreciated.