关于F2xx的库函数CAN_FilterInit

jklw0713

CAN_FilterInit 这个函数为什么只是对can1的设置，没有对can2？难道是我理解错了，can1 和can2 共用过滤器？
原函数：



/**
  * @brief  Configures the CAN reception filter according to the specified
  *         parameters in the CAN_FilterInitStruct.
  * @param  CAN_FilterInitStruct: pointer to a CAN_FilterInitTypeDef structure that
  *         contains the configuration information.
  * @retval None
  */
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;
}

jklw0713

回复【6楼】yyisme1988:
---------------------------------
嗯，我看了下你说的那个寄存器，这里的can1其实改成can就不会误导了。CAN_FMR的CAN2SB复位默认是0x0E，当设置
CAN_FilterNumber >=14就是can2设置了。
我加上这个
CAN_FilterInitStructure.CAN_FilterNumber=14;
CAN_FilterInit(&CAN_FilterInitStructure);
can2就好用了。

yyisme1988

回复【7楼】jklw0713:
---------------------------------
是的，默认为14~27号为can2使用，如果单独想使用can2也是可以的
在设置前加上
CAN_SlaveStartBank(N);
CAN_FilterInitStructure.CAN_FilterNumber=N;
当N= 0 的时候就只能用CAN2.
应该不是简单的把CAN1改成CAN,这个是硬件上的设计。

正点原子

是不是固件太老了？

jklw0713

回复【2楼】正点原子:
---------------------------------
也许是吧，反正我用can1 可以通信，改成can2没反应，我进去CAN_FilterInit 这个过滤器只是对can1的设置，请问can2要用过滤器不需要设置吗？

正点原子

回复【3楼】jklw0713:
---------------------------------
can2也有过滤器啊，不过我也没用过can2

jklw0713

回复【4楼】正点原子:
---------------------------------
嗯，谢谢，还是改硬件管脚吧，用can1

yyisme1988

lz，你好。我也一直被这个问题困扰，在网上找了一些资料也没有明确的答案，个人理解是应为CAN2没有直接访问SRAM的权限，所以对共用Filter组来说，只能通过CAN1来访问，那么如何实现CAN2的Filter设置呢？
不知道你有没有在意到CAN筛选器主寄存器CAN_FMR这个寄存器，当中有一个CAN2SB[5:0]这一个6位的操作位，当你设置这个位之后，硬件将对应的filter配置给CAN2,假设设置为N. 当你设置的CAN_FilterNumber >= N时，硬件就自动关联到CAN2的filter设置当中了。虽然你看的库函数一直只有CAN1->XXX操作，但实际上是可以对CAN2的filter进行设置的。 这是我的个人理解，不知道对不对，如lz有新的发现望指正

东方赤那

是的，默认为14~27号为can2使用，如果单独想使用can2也是可以的 
在设置前加上 
CAN_SlaveStartBank(N); 
CAN_FilterInitStructure.CAN_FilterNumber=N; 
当N= 0 的时候就只能用CAN2. 
应该不是简单的把CAN1改成CAN,这个是硬件上的设计。


受教了

敖厂长想成为

jklw0713 发表于 2014-11-13 11:53
回复【6楼】yyisme1988:
---------------------------------
嗯，我看了下你说的那个寄存器，这里的can1其 ...

你说的这两句CAN_FilterInitStructure.CAN_FilterNumber=14;
CAN_FilterInit(&CAN_FilterInitStructure); 应该加在什么地方？这里是要做一个case语句么请问。