最后一行的：CAN_FilterInit(&CAN_FilterInitStructure);//滤波器初始化
这个函数里面都是CAN1的寄存器设置哇，可CAN2就是能正常收发哇，CAN1和CAN2的地址也是不同的，这是啥情况呢？
#define CAN1_BASE             (APB1PERIPH_BASE + 0x6400)
#define CAN2_BASE             (APB1PERIPH_BASE + 0x6800)

void CAN_FilterInit(CAN_FilterInitTypeDef* CAN_FilterInitStruct)
{
  uint32_t filter_number_bit_pos = 0;
  /* Check the parameters */
  assert_param(IS_CAN_FILTER_NUMBER(CAN_FilterInitStruct->CAN_FilterNumber));
  assert_param(IS_CAN_FILTER_MODE(CAN_FilterInitStruct->CAN_FilterMode));
  assert_param(IS_CAN_FILTER_SCALE(CAN_FilterInitStruct->CAN_FilterScale));
  assert_param(IS_CAN_FILTER_FIFO(CAN_FilterInitStruct->CAN_FilterFIFOAssignment));
  assert_param(IS_FUNCTIONAL_STATE(CAN_FilterInitStruct->CAN_FilterActivation));

  filter_number_bit_pos = ((uint32_t)1) << CAN_FilterInitStruct->CAN_FilterNumber;

  /* Initialisation mode for the filter */
  CAN1->FMR |= FMR_FINIT;

  /* Filter Deactivation */
  CAN1->FA1R &= ~(uint32_t)filter_number_bit_pos;

  /* Filter Scale */
  if (CAN_FilterInitStruct->CAN_FilterScale == CAN_FilterScale_16bit)
  {
    /* 16-bit scale for the filter */
    CAN1->FS1R &= ~(uint32_t)filter_number_bit_pos;

    /* First 16-bit identifier and First 16-bit mask */
    /* Or First 16-bit identifier and Second 16-bit identifier */
    CAN1->sFilterRegister[CAN_FilterInitStruct->CAN_FilterNumber].FR1 =
       ((0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterMaskIdLow) << 16) |
        (0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterIdLow);

    /* Second 16-bit identifier and Second 16-bit mask */
    /* Or Third 16-bit identifier and Fourth 16-bit identifier */
    CAN1->sFilterRegister[CAN_FilterInitStruct->CAN_FilterNumber].FR2 =
       ((0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterMaskIdHigh) << 16) |
        (0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterIdHigh);
  }

  if (CAN_FilterInitStruct->CAN_FilterScale == CAN_FilterScale_32bit)
  {
    /* 32-bit scale for the filter */
    CAN1->FS1R |= filter_number_bit_pos;
    /* 32-bit identifier or First 32-bit identifier */
    CAN1->sFilterRegister[CAN_FilterInitStruct->CAN_FilterNumber].FR1 =
       ((0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterIdHigh) << 16) |
        (0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterIdLow);
    /* 32-bit mask or Second 32-bit identifier */
    CAN1->sFilterRegister[CAN_FilterInitStruct->CAN_FilterNumber].FR2 =
       ((0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterMaskIdHigh) << 16) |
        (0x0000FFFF & (uint32_t)CAN_FilterInitStruct->CAN_FilterMaskIdLow);
  }

  /* Filter Mode */
  if (CAN_FilterInitStruct->CAN_FilterMode == CAN_FilterMode_IdMask)
  {
    /*Id/Mask mode for the filter*/
    CAN1->FM1R &= ~(uint32_t)filter_number_bit_pos;
  }
  else /* CAN_FilterInitStruct->CAN_FilterMode == CAN_FilterMode_IdList */
  {
    /*Identifier list mode for the filter*/
    CAN1->FM1R |= (uint32_t)filter_number_bit_pos;
  }

  /* Filter FIFO assignment */
  if (CAN_FilterInitStruct->CAN_FilterFIFOAssignment == CAN_Filter_FIFO0)
  {
    /* FIFO 0 assignation for the filter */
    CAN1->FFA1R &= ~(uint32_t)filter_number_bit_pos;
  }

  if (CAN_FilterInitStruct->CAN_FilterFIFOAssignment == CAN_Filter_FIFO1)
  {
    /* FIFO 1 assignation for the filter */
    CAN1->FFA1R |= (uint32_t)filter_number_bit_pos;
  }

  /* Filter activation */
  if (CAN_FilterInitStruct->CAN_FilterActivation == ENABLE)
  {
    CAN1->FA1R |= filter_number_bit_pos;
  }

  /* Leave the initialisation mode for the filter */
  CAN1->FMR &= ~FMR_FINIT;
}