STM32的CAN过滤

简介

  STM32的CAN控制器可以对接收到的数据报文进行过滤。

1. 只接收指定CAN ID的数据。
2. 对于其他CAN ID发送过来的数据，则不再触发CAN中断。

  根据芯片的不同，可以有不同数量的CAN控制器：

• 如果STM32只有一个CAN控制器，则可以配置14个过滤器组，对应的编号为0 ~ 13。
• 如果STM32拥有两个CAN控制器，则可以配置28个过滤器组：

1. 对于CAN 1，对应的过滤器组编号为0 ~ 13。
2. 对于CAN 2，对应的过滤器组编号为14 ~ 27。

  CAN过滤有如下模式：

• 屏蔽位模式
• 标识符列表模式

相关寄存器

  和CAN过滤相关的寄存器为CAN_FxR1和CAN_FxR2：

  如果只想接收CAN ID为0x317的标准帧，则设置方法如下：

• 0110 0010 111：0x317对应的二进制位。
• 1111 1111 111：收到的数据帧中相应的ID位必须和设置的ID位一样。
• 00和11：只接收标准帧，不接收扩展帧。

  如果想接收CAN ID为0x310至0x317的标准帧，则设置方法如下：

代码实例

只过滤一个CAN ID

  如果需要让CAN 2只接收CAN ID为0x713的报文，则代码如下：

CAN_FilterInitTypeDef CAN_FilterInitStructure;

CAN_FilterInitStructure.CAN_FilterNumber = 14;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;

CAN_FilterInitStructure.CAN_FilterIdHigh     = ( uint16_t ) ( ( 0x713 << 5 ) & 0xFFFF );
CAN_FilterInitStructure.CAN_FilterIdLow      = ( uint16_t ) ( 0x0000 | CAN_ID_STD );
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0xFFF0;
CAN_FilterInitStructure.CAN_FilterMaskIdLow  = 0x0006;

CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit ( &CAN_FilterInitStructure );

过滤多个CAN ID

  如果需要让CAN 2只接收CAN ID为0x713、0x714的报文，则代码如下：

CAN_FilterInitTypeDef CAN_FilterInitStructure;

CAN_FilterInitStructure.CAN_FilterNumber = 14;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;

CAN_FilterInitStructure.CAN_FilterIdHigh     = ( uint16_t ) ( ( 0x713 << 5 ) & 0xFFFF );
CAN_FilterInitStructure.CAN_FilterIdLow      = ( uint16_t ) ( 0x0000 | CAN_ID_STD );
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0xFFF0;
CAN_FilterInitStructure.CAN_FilterMaskIdLow  = 0x0006;

CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit ( &CAN_FilterInitStructure );
/*-----------------------------------------------------------------------------------*/
CAN_FilterInitStructure.CAN_FilterNumber = 15;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;

CAN_FilterInitStructure.CAN_FilterIdHigh     = ( uint16_t ) ( ( 0x714 << 5 ) & 0xFFFF );
CAN_FilterInitStructure.CAN_FilterIdLow      = ( uint16_t ) ( 0x0000 | CAN_ID_STD );
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0xFFF0;
CAN_FilterInitStructure.CAN_FilterMaskIdLow  = 0x0006;

CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
CAN_FilterInit ( &CAN_FilterInitStructure );