&TxMessage

&TxMessage是指向CAN消息结构体的指针，用于在CAN总线发送数据时传递消息结构体的地址。在HAL库中，CAN消息结构体的定义如下：

typedef struct {
  uint32_t StdId;   /*!< Specifies the standard identifier.
                         This parameter can be a value between 0 to 0x7FF. */
  uint32_t ExtId;   /*!< Specifies the extended identifier.
                         This parameter can be a value between 0 to 0x1FFFFFFF. */
  uint32_t IDE;     /*!< Specifies the type of identifier for the message that will be transmitted.
                         This parameter can be a value of @ref CAN_identifier_type */
  uint32_t RTR;     /*!< Specifies the type of frame for the message that will be transmitted.
                         This parameter can be a value of @ref CAN_remote_transmission_request */
  uint32_t DLC;     /*!< Specifies the length of the frame that will be transmitted.
                         This parameter can be a value between 0 to 8 */
  uint8_t  Data[8]; /*!< Contains the data to be transmitted.
                         This parameter must be a value between 0 to 0xFF */
} CanTxMsgTypeDef;

可以看到，CAN消息结构体包含了标准标识符、扩展标识符、标识符类型、帧类型、数据长度和数据等信息。在使用HAL_CAN_AddTxMessage或HAL_CAN_Transmit函数时，需要将CAN消息结构体的地址传递给&TxMessage参数，以便函数能够正确地发送数据到CAN总线上。