求分析CAN发送在LOOPBACK下可以，NORMAL模式无输出

void rt_hw_can_init(void)

{

        NVIC_InitTypeDef                                NVIC_InitStructure;

        GPIO_InitTypeDef                                GPIO_InitStructure;

        CAN_InitTypeDef                                        CAN_InitStructure;

        CAN_FilterInitTypeDef                CAN_FilterInitStructure;



        /* CAN Periph clock enable */

        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOD | RCC_AHB1Periph_GPIOF  ,ENABLE);

        RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);



        GPIO_PinAFConfig (GPIOB,GPIO_PinSource8|GPIO_PinSource9,GPIO_AF_CAN1); 

        /* Configure CAN pin: RX & TX*/

        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;        

        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

        GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

        GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;

        GPIO_Init(GPIOB, &GPIO_InitStructure);   

        /* CAN register init */

        CAN_DeInit(CAN1);

        CAN_StructInit(&CAN_InitStructure);



  /* CAN cell init */

        CAN_InitStructure.CAN_TTCM = DISABLE;

        CAN_InitStructure.CAN_ABOM = DISABLE;

        CAN_InitStructure.CAN_AWUM = DISABLE;

        CAN_InitStructure.CAN_NART = DISABLE;

        CAN_InitStructure.CAN_RFLM = DISABLE;

        CAN_InitStructure.CAN_TXFP = DISABLE;

//         CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;

        CAN_InitStructure.CAN_Mode = CAN_Mode_LoopBack;

        /* CAN Baudrate = 1 MBps (CAN clocked at 32 MHz) */

        CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;

        CAN_InitStructure.CAN_BS1 = CAN_BS1_5tq;//CAN_BS1_6tq;

        CAN_InitStructure.CAN_BS2 = CAN_BS2_2tq;//CAN_BS2_5tq;

        CAN_InitStructure.CAN_Prescaler = 4;//3;



        /*Initializes the CAN1 */

        CAN_Init(CAN1, &CAN_InitStructure);



        CAN_FilterInitStructure.CAN_FilterNumber=0;

        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=0;

        CAN_FilterInitStructure.CAN_FilterActivation=ENABLE;

        CAN_ITConfig(CAN1,CAN_IT_FMP0, ENABLE);

        CAN_FilterInit(&CAN_FilterInitStructure);

        

        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

        /* Enable CAN1 RX0 interrupt IRQ channel */

        NVIC_InitStructure.NVIC_IRQChannel = CAN1_RX0_IRQn;

        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;

        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

        NVIC_Init(&NVIC_InitStructure);

        /* IT Configuration for CAN1 */  

        CAN_ITConfig(CAN1, CAN_IT_FMP0, ENABLE);

        

        rt_kprintf("CAN thread is started!!! Speed is 1MHz!!! \r\n");

}

GPIO_PinAFConfig (GPIOB,GPIO_PinSource8,GPIO_AF_CAN1); 

        GPIO_PinAFConfig (GPIOB,GPIO_PinSource9,GPIO_AF_CAN1);

        /* Configure CAN pin: RX */

        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;//| GPIO_Pin_9;

        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

        GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

        GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;

        GPIO_Init(GPIOB, &GPIO_InitStructure); 

        /* Configure CAN pin: TX */

        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

        GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

        GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;

        GPIO_Init(GPIOB, &GPIO_InitStructure);