Help needed with STM32 discovery and I2C

[gdelpu]

Posted on April 12, 2011 at 13:49

Dear all,

My name is Gregory and I live in France (so excuse my poor english). I am a newbie in STM32 world, but I come from the Arduino world and have some good basis in C programing.

I try to use a DS1307 chip with my discovery board but I'm facing a problem for a few days now that I can't overcome.

Here below is the code of my main.c file, I try to read values in the RTC DS1307 chip, I sniff the I2C bus with a logic analyzer and I can clearly see the start command followed by the slave adresse + the direction bit and then a NACK, the chip is working (tested on my arduino board) and I can't understand why I get a NACK (I expect the slave to ACK and then send the bytes from the eeprom). Moreover, I never get the event EV6

I will be great if you can help me.

Code : 

&sharpinclude ''stm32f10x.h''

&sharpdefine I2C_SPEED       100000 /*!< I2C Speed */

&sharpdefine I2C1_SLAVE_ADDRESS7 0b11010000

&sharpdefine I2C_TIMEOUT            100000

GPIO_InitTypeDef GPIO_InitStructureOutput; // Structure for Output Definitions

GPIO_InitTypeDef GPIO_InitStructureI2C; // Structure for I2C Definitions

I2C_InitTypeDef I2C_InitStructure; // Structure for I2

/* Private functions ---------------------------------------------------------*/

/**

  * @brief  Main program

  * @param  None

  * @retval : None

  */

int main(void)

{

 GPIO_InitTypeDef GPIO_InitStructure;

 I2C_InitTypeDef  I2C_InitStructure;

 int   TimeOut;

 /* GPIOB Periph clock enable */

 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

 /* I2C1 and I2C2 Periph clock enable */

 RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

 /* Configure I2C1 pins: SCL and SDA ----------------------------------------*/

 GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | GPIO_Pin_7;

 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD; // Open Drain, I2C bus pulled high externally

 GPIO_Init(GPIOB, &GPIO_InitStructure);

 /* Enable I2C1 -------------------------------------------------------------*/

 I2C_DeInit(I2C1);

 I2C_Cmd(I2C1, ENABLE);

 /* I2C1 configuration ------------------------------------------------------*/

 I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;

 I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;

 I2C_InitStructure.I2C_OwnAddress1 = 0x039;

 I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;

 I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;

 I2C_InitStructure.I2C_ClockSpeed = I2C_SPEED;

 I2C_Init(I2C1, &I2C_InitStructure);

 /*----- Transmission Phase -----*/

 /* Send I2C1 START condition */

 I2C_GenerateSTART(I2C1, ENABLE);

 /* Test on I2C1 EV5 and clear it */

 TimeOut = I2C_TIMEOUT;

 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT))

 {

 TimeOut--;

 if (TimeOut == 0) return 1;

 }

 I2C_SendData(I2C1, 0x00); // Send Year register address

 /* Send DS1307 slave Address for write */

 I2C_Send7bitAddress(I2C1, I2C1_SLAVE_ADDRESS7, I2C_Direction_Transmitter);

  //Test on I2C1 EV6 and clear it

 TimeOut = I2C_TIMEOUT;

 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))

 {

 TimeOut--;

 if (TimeOut == 0){

 // Send I2C1 STOP Condition

 I2C_GenerateSTOP(I2C1, ENABLE);

 return 2;

 }

 }

 return 1;

}

#i2c-ds1307