I2C DMA

[pranathi1091]

Posted on January 11, 2013 at 10:33

Hello All,

I am programing an EEPROM which is interfaced to STM32 via I2c2. I am using DMA interrupt for reading data from EEPROM location. I feel Writing to EEPROM works fine and could see TxE and TRA flags set while trsanmitting the data from STM. But i have problem in redaing data from EEPROM. I can see no flags set when i watch the registers. The DMA interrupt occurs but DMA_FLAG_TCIF0 doesnt get clerared. Either I am able to see some data in the buffer. I have posted the code.Please let me know where am I going wrong

void  ReadBuffer(uint8_t* pBuffer, uint16_t ReadAddr, uint16_t* NumByteToRead)

 {  uint16_t data;  uint8_t i;  ptEEDataReadPointer=NumByteToRead;  //  While the bus is busy   Timeout=LONG_TIMEOUT;    while(I2C_GetFlagStatus(I2C2, I2C_FLAG_BUSY))    {    Timeout--;   if (Timeout==0)   {   return TIMEOUT_ERROR;   }   }    //Send START condition  I2C_GenerateSTART(I2C2,ENABLE);  //Test on EV5 and clear it (cleared by reading SR1 then writing to DR)

 if(!I2C_CheckEvent(I2C2, I2C_EVENT_MASTER_MODE_SELECT))

 {   I2C_GenerateSTART(I2C2,ENABLE);  }    Timeout=FLAG_TIMEOUT;    while(!I2C_CheckEvent(I2C2, I2C_EVENT_MASTER_MODE_SELECT))    {  Timeout--;     if(Timeout == 0)  {  return TIMEOUT_ERROR;   }   }   I2C_Send7bitAddress(I2C2, nEEAddress, I2C_Direction_Transmitter);

  //Test on EV6 and clear it

   if(!I2C_CheckEvent(I2C2, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))    {     I2C_GenerateSTART(I2C2,ENABLE);  I2C_Send7bitAddress(I2C2, nEEAddress, I2C_Direction_Transmitter);  }

   I2C_SendData(I2C2, ReadAddr); 

  //Test on EV8 and clear it

  Timeout = FLAG_TIMEOUT;

  data = I2C1->DR;

  //Send STRAT condition a second time   I2C_GenerateSTART(I2C2, ENABLE);     //Test on EV5 and clear it (cleared by reading SR1 then writing to DR)   Timeout = FLAG_TIMEOUT;   while(!I2C_CheckEvent(I2C2, I2C_EVENT_MASTER_MODE_SELECT))   {     if((Timeout--) == 0) return TIMEOUT_ERROR;   }    //Send EEPROM address for read   I2C_Send7bitAddress(I2C2, nEEAddress, I2C_Direction_Receiver);      /* If number of data to be read is 1, then DMA couldn't be used */   /* One Byte Master Reception procedure (POLLING) */   if ((uint16_t)(*NumByteToRead) < 2)   {         //Disable Acknowledgment     I2C_AcknowledgeConfig(I2C2, DISABLE);           //Clear ADDR register by reading SR1 then SR2 register (SR1 has already been read)     (void)I2Cx->SR2;                    // Read the byte received from the EEPROM     *pBuffer = I2C_ReceiveData(I2Cx);  

  //Send STOP Condition

  I2C_GenerateSTOP(I2Cx, ENABLE);     /*!< Decrement the read bytes counter */     (uint16_t)(*NumByteToRead)--;                /* Wait to make sure that STOP control bit has been cleared */     Timeout = FLAG_TIMEOUT;     while(I2Cx->CR1 & I2C_CR1_STOP)     {       if((Timeout--) == 0)    return TIMEOUT_ERROR;     }      Here is my Interrupt service routine

void DMA1_Stream3_IRQHandler(void)

{  //Check if the DMA transfer is complete   if(DMA_GetFlagStatus(DMA1_Stream3, DMA_FLAG_TCIF0) != RESET)   {          //Send STOP Condition     I2C_GenerateSTOP(I2Cx, ENABLE);            //Disable the DMA Rx Stream and Clear TC Flag */      DMA_Cmd(Stream3, DISABLE);     DMA_ClearFlag(Stream3, DMA_FLAG_TCIF0);              *ptEEDataReadPointer = 0;    } Thanks #i

[harry_rostovtsev]

Posted on September 12, 2014 at 01:00

You're running DMA1_Stream3 but checking DMA_FLAG_TCIF0.  You need to be checking DMA_FLAG_TCIF3 (which matches Stream3).

void DMA1_Stream3_IRQHandler(void)

{

 //Check if the DMA transfer is complete   if(DMA_GetFlagStatus(DMA1_Stream3, DMA_FLAG_TCIF0) != RESET)   {          //Send STOP Condition     I2C_GenerateSTOP(I2Cx, ENABLE);            //Disable the DMA Rx Stream and Clear TC Flag */      DMA_Cmd(Stream3, DISABLE);     DMA_ClearFlag(Stream3, DMA_FLAG_TCIF0);              *ptEEDataReadPointer = 0;    } Thanks