I2C doesn't work!

Posted on October 15, 2014 at 11:38

Please, help me into get out of this trouble!

I' am working on discovery board STM32F429L-disco. In order to have an I2C available to drive an external device, I am using PC9 ad PA8 pins (I2C3), that are also used to drive the on board touch screen controller. (in orther to be sure I have also desoldered the controller from the board to have a plenty free I2C bus!!)

The two pull up on the line are connected, so I can see with the scope the two line normally high.

I use the following code to set the pin and to start and configure the peripheral:

RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C3, ENABLE); //Enable I2C3 peripheral clock

  RCC_AHB1PeriphClockCmd(GYRO_I2C_SDA_GPIO_CLK, ENABLE); //Enable gpio pin clock

  

  RCC_AHB1PeriphClockCmd(GYRO_I2C_SCL_GPIO_CLK, ENABLE); //Enable gpio pin clock

  GPIO_PinAFConfig(GYRO_I2C_SDA_PORT, GYRO_I2C_SDA_SOURCE, GYRO_I2C_SDA_AF);

  GPIO_PinAFConfig(GYRO_I2C_SCL_PORT, GYRO_I2C_SCL_SOURCE, GYRO_I2C_SCL_AF);

  

  /* Configure the GPIO_GYRO_I2C_SDA pin */

  GPIO_InitStructure.GPIO_Pin = GYRO_I2C_SDA_PIN;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GYRO_I2C_SDA_PORT, &GPIO_InitStructure);

  

 

  /* Configure the GPIO_GYRO_I2C_SCL in */

  GPIO_InitStructure.GPIO_Pin = GYRO_I2C_SCL_PIN;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GYRO_I2C_SCL_PORT, &GPIO_InitStructure);

  

   

  /* Configure the I2C init structure */

  

  I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;

  I2C_InitStructure.I2C_ClockSpeed = 100000;

  I2C_InitStructure.I2C_OwnAddress1 = 0xA0;

  I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;

  I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;

  I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;

  I2C_Init(GYRO_I2C, &I2C_InitStructure);

  

  I2C_Cmd(GYRO_I2C, ENABLE);

////

here also all the define:

#define GYRO_I2C                           I2C3

#define GYRO_I2C_CLK                       RCC_APB1Periph_I2C3

#define GYRO_I2C_SDA_PIN                   GPIO_Pin_9

#define GYRO_I2C_SDA_PORT                  GPIOC

#define GYRO_I2C_SDA_GPIO_CLK              RCC_AHB1Periph_GPIOC

#define GYRO_I2C_SDA_SOURCE                GPIO_PinSource9

#define GYRO_I2C_SDA_AF                    GPIO_AF_I2C3

#define GYRO_I2C_SCL_PIN                   GPIO_Pin_8

#define GYRO_I2C_SCL_PORT                  GPIOA

#define GYRO_I2C_SCL_GPIO_CLK              RCC_AHB1Periph_GPIOA

#define GYRO_I2C_SCL_SOURCE                GPIO_PinSource8

#define GYRO_I2C_SCL_AF                    GPIO_AF_I2C3

In the main program I call the: I2C_GenerateSTART(GYRO_I2C, ENABLE);

and the : I2C_Send7bitAddress(GYRO_I2C, 0x55, I2C_Direction_Receiver);

After the start generation setting I aspect ther the peripheral is in master mode as wrote on the referance manual, but nothing happen! the two line remein high to clock generation no data.

I also tried to add this control

while ((!I2C_CheckEvent(GYRO_I2C, I2C_EVENT_MASTER_MODE_SELECT)))

  {} 

and discovered that the I2C_EVENT_MASTER_MODE_SELECT condition is never true! so seems that the peripheral is not in master mode or is not active also after a start condition generation request.

Please, can you tell me where I am wrong?

thanks