Filter setting of can

CAN Node passing ID Filtering can selectively receive messages ,stm32 Of CAN The filter has two modes ： List mode and mask mode .

（1） List mode

List mode only receives those that meet the specified ID Frame of , Save the specified ID Use 2 individual 32 Bit register , It is divided into 16 Bit mode and 32 Bit mode .

16 Bit list mode one ID Occupy 16 position , A coexistence 4 individual 16 position ID, Usually used for standard frames , Standard frame ID Deposit in 16 The height of a bit 11 position , Extended frames can only be saved 15~17 Yu low 3 position , The other two save RTR and IDE position , Respectively represent standard frames (0)/ Extended frames (1), Data frame (0)/ Remote control frame (1)

32 Bit list mode one ID Occupy 32 position , A coexistence 2 individual 32 position ID, Usually used to extend frames , Extended frame ID Deposit in 32 High bit register 29 position , in addition 3 Bits are stored separately IDE,RTR and 0.

// Initialize filter ------16 Bit list mode 
	CAN_FilterInitStruct.CAN_FilterActivation = ENABLE;// Enable filter 
	CAN_FilterInitStruct.CAN_FilterFIFOAssignment = CAN_Filter_FIFO0;// Install the filter to FIFO0
	CAN_FilterInitStruct.CAN_FilterMode = CAN_FilterMode_IdList;// Filter mode  ---  list 
	CAN_FilterInitStruct.CAN_FilterNumber = 0;// filter 0
	CAN_FilterInitStruct.CAN_FilterScale = CAN_FilterScale_16bit;// Filter length 
// Provide two standard frames ID 0x123 , 0x321; Provide two masks 0x7af,0x000
	CAN_FilterInitStruct.CAN_FilterIdHigh = 0x123<<5;
	CAN_FilterInitStruct.CAN_FilterIdLow = 0x321<<5;
	CAN_FilterInitStruct.CAN_FilterMaskIdHigh = 0x7af<<5;
	CAN_FilterInitStruct.CAN_FilterMaskIdLow = 0x000;
	CAN_FilterInit(&CAN_FilterInitStruct);




// Initialize filter ------16 Bit mask mode 
	CAN_FilterInitStruct.CAN_FilterActivation = ENABLE;// Enable filter 
	CAN_FilterInitStruct.CAN_FilterFIFOAssignment = CAN_Filter_FIFO0;// Install the filter to FIFO0
	CAN_FilterInitStruct.CAN_FilterMode = CAN_FilterMode_IdList;// Filter mode  --- list 
	CAN_FilterInitStruct.CAN_FilterNumber = 0;// filter 0
	CAN_FilterInitStruct.CAN_FilterScale = CAN_FilterScale_16bit;// Filter length 

// Provide a standard frame ID 0x6789abc,0xcba9876
//ID high 16 position 
	CAN_FilterInitStruct.CAN_FilterIdHigh = 0x6789abc>>13;
//ID low 13 Put high position ,IDE-1
	CAN_FilterInitStruct.CAN_FilterIdLow = （0x6789abc<<5）& 0xffff | (0x1)<<2;
//ID high 16 position 
	CAN_FilterInitStruct.CAN_FilterMaskIdHigh = 0xcba9876>>13;
//ID low 13 Put high position ,IDE-1
	CAN_FilterInitStruct.CAN_FilterMaskIdLow = （0xcba9876<<3）& 0xffff | (0x1)<<2;
	CAN_FilterInit(&CAN_FilterInitStruct);

（2） Mask mode

Mask mode only receives frames that meet the mask requirements , One 32 Bit register storage ID, One 32 Bit register storage mask , Also divided into 16 Bit mode and 32 Bit mode .

Only the first register corresponds to 1 You need to match for .

// Initialize filter ------16 Bit mask mode 
	CAN_FilterInitStruct.CAN_FilterActivation = ENABLE;// Enable filter 
	CAN_FilterInitStruct.CAN_FilterFIFOAssignment = CAN_Filter_FIFO0;// Install the filter to FIFO0
	CAN_FilterInitStruct.CAN_FilterMode = CAN_FilterMode_IdMask;// Filter mode  ---  list 
	CAN_FilterInitStruct.CAN_FilterNumber = 0;// filter 0
	CAN_FilterInitStruct.CAN_FilterScale = CAN_FilterScale_16bit;// Filter length 
// Provide two standard frames ID 0x123 , 0x321; Provide two masks 0x0f0,0xf0f0
	CAN_FilterInitStruct.CAN_FilterIdHigh = 0x123<<5;
	CAN_FilterInitStruct.CAN_FilterIdLow = 0x321<<5;
	CAN_FilterInitStruct.CAN_FilterMaskIdHigh = 0x0f0<<5;
	CAN_FilterInitStruct.CAN_FilterMaskIdLow = ((0xcba9876<<3) & 0xffff)|(0x1<<2);
	CAN_FilterInit(&CAN_FilterInitStruct);

  Please try setting CN Bus filter 32 Bit mode