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STM32F103VET6 CAN Normal mode issue

muhammaduzairafzal45
Associate III

‎2013-04-22 06:07 AM

Posted on April 22, 2013 at 15:07

STM32F103 has one CAN only. I want to send and receive data using the same CAN in normal mode(For testing purpose, CAN sends and receives message itself ). I have tried loopback mode and it worked fine. But when I configure CAN to normal mode it does not send or receive message at all over CAN. The CAN Tx pin is not showing CAN transmitted message on oscillioscope(In  loopback it shows message correctly). Firstly I have used method described at  

www.mikrocontroller.net/attachment/28831/siemens_AP2921.pdf  

which tells a method to use CAN without transceiver using diodes. Then I thought may be this method is not working so I used a transceiver but I was unable to solve the problem. I am sure that it is not the software problem. What am I doing wrong?

int main(void)

{

USART2_Config();

USART2_SendData_s(''Main Start:\n\r'');

CAN_Config();

transmit_message();

  while (1)

{

}

}

void CAN_Config(void)

{

// Enable GPIOA clock                                                   

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO , ENABLE);

// CAN Periph clock enable 

RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1 , ENABLE);

// GPIO CAN_RX Configuration 

GPIO_InitStructureCAN_RX.GPIO_Pin = GPIO_Pin_11;

GPIO_InitStructureCAN_RX.GPIO_Mode = GPIO_Mode_IPU;

GPIO_InitStructureCAN_RX.GPIO_Speed = GPIO_Speed_10MHz;

GPIO_Init(GPIOA, &GPIO_InitStructureCAN_RX);

// GPIO CAN_TX  Configuration 

GPIO_InitStructureCAN_TX.GPIO_Pin = GPIO_Pin_12;

GPIO_InitStructureCAN_TX.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_InitStructureCAN_TX.GPIO_Speed = GPIO_Speed_10MHz;

GPIO_Init(GPIOA, &GPIO_InitStructureCAN_TX);

// CAN1 Filter,FIFO and Baudrate settings 

CAN_Struct_Init();

// CAN1 NVIC settings for FIFO 0 

  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

  NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn;

  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0;

  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x05;

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  NVIC_Init(&NVIC_InitStructure);

// IT Configuration for CAN1 FIFO 0 message received interrupt

CAN_ITConfig(CAN1, CAN_IT_FMP0, ENABLE);

// Receive message initialized

RxMessage.StdId = 0x00;

RxMessage.ExtId = 0x00;

RxMessage.IDE = CAN_ID_STD;

RxMessage.DLC = 0;

  RxMessage.FMI = 0;

  for (i = 0; i < 8; i++)

  {

    RxMessage.Data[i] = 0;

  }

}

void CAN_Struct_Init(void)

{

  // CAN1 register init 

  CAN_DeInit(CAN1);

CAN_StructInit(&CAN_InitStructure); 

  // CAN1 cell init 

CAN_InitStructure.CAN_TTCM = DISABLE; // time-triggered communication mode = DISABLED

CAN_InitStructure.CAN_ABOM = DISABLE; // automatic bus-off management mode = DISABLED

CAN_InitStructure.CAN_AWUM = DISABLE; // automatic wake-up mode = DISABLED

CAN_InitStructure.CAN_NART = DISABLE; // non-automatic retransmission mode = DISABLED

CAN_InitStructure.CAN_RFLM = DISABLE; // receive FIFO locked mode = DISABLED

CAN_InitStructure.CAN_TXFP = DISABLE; // transmit FIFO priority = DISABLED

  CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;

  CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;

CAN_InitStructure.CAN_BS1 = CAN_BS1_2tq;

  CAN_InitStructure.CAN_BS2 = CAN_BS2_3tq;

  // CAN1 Baudrate = 250kbps (System clock and CAN clock is 24MHz)

// CAN_Prescaler value= CAN_clock/(required_Baudrate*total_number_of_tq)

// In present case, total_number_of_tq=CAN_SJW_1tq+CAN_BS1_2tq+CAN_BS2_3tq=6*tq

// so CAN_Prescaler= 24MHz/(250kbps*6)=16

  

  CAN_InitStructure.CAN_Prescaler = 16;

  if(CAN_Init(CAN1, &CAN_InitStructure)==CANINITOK)

USART2_SendData_s(''Init OK:\n\r'');

else

USART2_SendData_s(''Init Fail:\n\r'');

  // CAN filter init 

  CAN_FilterInitStructure.CAN_FilterNumber = 2;

  CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;

  CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;

  CAN_FilterInitStructure.CAN_FilterIdHigh = 0x0000;

  CAN_FilterInitStructure.CAN_FilterIdLow = 0x0000;

  CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;

  CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;

CAN_FilterInitStructure.CAN_FilterFIFOAssignment = CAN_FilterFIFO0;

  CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;

  CAN_FilterInit(&CAN_FilterInitStructure);

}

void transmit_message(void)

{

Delay(0xffff);

// Transmit message initialized

  TxMessage.StdId=0x00;

TxMessage.ExtId=0x00;

  TxMessage.RTR=CAN_RTR_DATA;

  TxMessage.IDE=CAN_ID_STD;

  TxMessage.DLC=5;

  TxMessage.Data[0]=0xA1;

  TxMessage.Data[1]=0xB2;

TxMessage.Data[2]=0xC3;

TxMessage.Data[3]=0xD4;

TxMessage.Data[4]=0xE5;

  TransmitMailbox=CAN_Transmit(CAN1, &TxMessage);

  i = 0;

  while((CAN_TransmitStatus(CAN1, TransmitMailbox) != CANTXOK) && (i != 0xFFFF))

  {

    i++;

  }

USART2_SendData_s(''Succeed:\n\r'');

}

void USB_LP_CAN1_RX0_IRQHandler(void)

{

if(CAN_GetITStatus(CAN1, CAN_IT_FMP0) != RESET)

{

USART2_SendData_s(''CAN FIFO 0 IRQ:\n\r'');

CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);

  }

}

#can #can #stm32-can
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6 REPLIES 6
jpeacock2399
Associate II

‎2013-04-22 06:50 AM

Posted on April 22, 2013 at 15:50

You can enable an internal loopback with: 

CAN_InitStructure.CAN_Mode = CAN_Mode_Silent_LoopBack; // silent loopback mode, bus disconnect, debugging

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muhammaduzairafzal45
Associate III

‎2013-04-22 07:16 AM

Posted on April 22, 2013 at 16:16

Loopback and silent+loopback is working fine as expected.... I don't understand why it is not sending message in normal mode. Please guide!!

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Tesla DeLorean
Guru

‎2013-04-22 08:05 AM

Posted on April 22, 2013 at 17:05

Send a continuous stream of messages.

Make sure USART1 isn't using flow control.

Consider remapping CAN to PB8/9. (STM3210E-EVAL uses this)

Get some boards with CAN designed on, experiment with them. Absent hardware review schematics. Known working hardware will avoid fighting your own issues.

Make sure CAN transceivers are enabled.

I used 125 kbps on the STM3210E

CAN_InitStructure.CAN_TXFP = ENABLE;
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jpeacock2399
Associate II

‎2013-04-22 12:11 PM

Posted on April 22, 2013 at 21:11

Do you have both nodes in normal mode and are both transceivers terminated?  CAN won;t run in normal mode with just one node.

  Jack Peacock
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muhammaduzairafzal45
Associate III

‎2013-04-22 10:37 PM

Posted on April 23, 2013 at 07:37

please clarify Why at least two CANs must be used? I did not undersatnd why cannot I test one CAN alone in normal mode? I have tried one node system as well as two node system but using diode method(not transceivers as I have only one transceiver at this time so I have to shift my method to diodes as described preveously.)

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muhammaduzairafzal45
Associate III

‎2013-04-25 04:15 AM

Posted on April 25, 2013 at 13:15

I am still unable to figure out what is wrong with the normal mode of CAN. why is only loopback test works? In normal mode , CAN.Tx pin should response at least but it does not response at all. Please help out. I have also viewed several similar post for STM32F103 CAN normal mode problem but nobody have answered the issue. Is this problem is only with STM32F103 series?

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