STM32F103 bxCAN not working

Question

I'm trying to make use of the bxCAN of STM32F103C8 on a bluepill but it doesn't work and I don't know what is the problem.I'm using the hal API
here is the main code in the while loop

while (1)
{
    char msg[50];
    CAN_TxHeaderTypeDef TxHeader;
    uint8_t data[5] = {'H','E','L','L','O'};
    uint32_t TxMailbox;
    TxHeader.DLC = 5;
    TxHeader.ExtId = 0x18181820;
    TxHeader.IDE = CAN_ID_EXT;
    TxHeader.RTR = CAN_RTR_DATA;
    if(HAL_CAN_AddTxMessage(&hcan, &TxHeader, data,TxMailbox) != HAL_OK){
        Error_Handler();
    }

    while(HAL_CAN_IsTxMessagePending(&hcan, TxMailbox));
    HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
    HAL_Delay(1000);
    HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
    HAL_Delay(1000);
}

The code breaks at the HAL_CAN_AddTxMessage.
this is my first time working with an STM32 so I've never had a working example and couldn't find any working examples online.
Please help I've posted many times :/

Answer 1

TxMailbox -> &TxMailbox.

The manual:

pTxMailbox pointer to a variable where the function will return the TxMailbox used to store the Tx message.

Since the function will apparently try to return data through this pointer, it will crash and burn if you provide a uint32_t by value.

Notably, a conforming C compiler must give you a message (warning or error) for this code. If you didn't get any such message, your tool chain is broken. References.