STM32 HAL CAN does not update value and crashes when setting ExtId

Question

I'm running my first CAN test program using STM32CubeMX, STM32F103C8T6 and Eclipse.

I used default CAN settings in STM32CubeMX (also tried loopback but the results are equal).

What I see (see pic below) is two things I do not understand;

• In the picture below, you can see I exceeded the line with hcan.pTxMsg->StdId = 0x321 (left red oval), but the current value shows 536891392 (right red oval).

• When I execute the next line (green): hcan.pTxMsg->ExtId = 0x01, I end up in a hard fault interrupt:

  /**

  • @brief This function handles Hard fault interrupt. / void HardFault_Handler(void) { / USER CODE BEGIN HardFault_IRQn 0 */

    /* USER CODE END HardFault_IRQn 0 / while (1) { } / USER CODE BEGIN HardFault_IRQn 1 */

    /* USER CODE END HardFault_IRQn 1 */ }

Why is the value not updated and why do I get a hardware fault (the pointer hcan.pTxMsg is not NULL since it even displays the field StdId (it even can display ExtId which has value 134222077 (not shown in pic below)?

Answer 1

By default STM32CubeMx create the initialization code for 'can' (if selected). This code can be found in MX_CAN_Init and is called by main.

However, it does not assign/initialize the pRxMsg and pTxMsg.

The pTxMsg should be defined as:

CanTxMsgTypeDef txMessage;
hcan.pTxMsg = &txMessage;

and the pRxMsg as:

CanRxMsgTypeDef rxMessage;
hcan.pRxMsg = &rxMessage;