How to configure CAN filters to use CAN1 and CAN2 parallelly.

[SPeri.1]

Both CAN buses are transmitting correctly. But when I initialize CAN1 and CAN2 only CAN2 receives messages, when only CAN2 is initialized it receives. same for the CAN1. Here I attached my initializing function.

static void MX_CAN1_Init(void)

{



 /* USER CODE BEGIN CAN1_Init 0 */



 /* USER CODE END CAN1_Init 0 */



 /* USER CODE BEGIN CAN1_Init 1 */



 /* USER CODE END CAN1_Init 1 */

 hcan1.Instance = CAN1;

 hcan1.Init.Prescaler = 16;

 hcan1.Init.Mode = CAN_MODE_NORMAL;

 hcan1.Init.SyncJumpWidth = CAN_SJW_1TQ;

 hcan1.Init.TimeSeg1 = CAN_BS1_12TQ;

 hcan1.Init.TimeSeg2 = CAN_BS2_5TQ;

 hcan1.Init.TimeTriggeredMode = DISABLE;

 hcan1.Init.AutoBusOff = DISABLE;

 hcan1.Init.AutoWakeUp = DISABLE;

 hcan1.Init.AutoRetransmission = DISABLE;

 hcan1.Init.ReceiveFifoLocked = DISABLE;

 hcan1.Init.TransmitFifoPriority = DISABLE;

 if (HAL_CAN_Init(&hcan1) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN CAN1_Init 2 */

 CAN_FilterTypeDef can_filter_config1;

 can_filter_config1.FilterActivation = CAN_FILTER_ENABLE;

 can_filter_config1.FilterBank = 10;

 can_filter_config1.FilterFIFOAssignment = CAN_FILTER_FIFO0;

 can_filter_config1.FilterIdHigh = 0;

 can_filter_config1.FilterIdLow = 0x0000;

 can_filter_config1.FilterMaskIdHigh = 0;

 can_filter_config1.FilterMaskIdLow = 0x0000;

 can_filter_config1.FilterMode = CAN_FILTERMODE_IDMASK;

 can_filter_config1.FilterScale = CAN_FILTERSCALE_32BIT;

 can_filter_config1.SlaveStartFilterBank = 0;



 HAL_CAN_ConfigFilter(&hcan1, &can_filter_config1);



 /* USER CODE END CAN1_Init 2 */



}



/**

 * @brief CAN2 Initialization Function

 * @PAram None

 * @retval None

 */

static void MX_CAN2_Init(void)

{



 /* USER CODE BEGIN CAN2_Init 0 */



 /* USER CODE END CAN2_Init 0 */



 /* USER CODE BEGIN CAN2_Init 1 */



 /* USER CODE END CAN2_Init 1 */

 hcan2.Instance = CAN2;

 hcan2.Init.Prescaler = 16;

 hcan2.Init.Mode = CAN_MODE_NORMAL;

 hcan2.Init.SyncJumpWidth = CAN_SJW_1TQ;

 hcan2.Init.TimeSeg1 = CAN_BS1_12TQ;

 hcan2.Init.TimeSeg2 = CAN_BS2_5TQ;

 hcan2.Init.TimeTriggeredMode = DISABLE;

 hcan2.Init.AutoBusOff = DISABLE;

 hcan2.Init.AutoWakeUp = DISABLE;

 hcan2.Init.AutoRetransmission = DISABLE;

 hcan2.Init.ReceiveFifoLocked = DISABLE;

 hcan2.Init.TransmitFifoPriority = DISABLE;

 if (HAL_CAN_Init(&hcan2) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN CAN2_Init 2 */

 CAN_FilterTypeDef can_filter_config2;

 can_filter_config2.FilterActivation = CAN_FILTER_ENABLE;

 can_filter_config2.FilterBank = 1;

 can_filter_config2.FilterFIFOAssignment = CAN_FILTER_FIFO1;

 can_filter_config2.FilterIdHigh = 0;

 can_filter_config2.FilterIdLow = 0x0000;

 can_filter_config2.FilterMaskIdHigh = 0;

 can_filter_config2.FilterMaskIdLow = 0x0000;

 can_filter_config2.FilterMode = CAN_FILTERMODE_IDMASK;

 can_filter_config2.FilterScale = CAN_FILTERSCALE_32BIT;

 can_filter_config2.SlaveStartFilterBank = 1;



 HAL_CAN_ConfigFilter(&hcan2, &can_filter_config2);



 /* USER CODE END CAN2_Init 2 */



}

[Foued_KH]

Hello @SPeri.1​ ,

which board do you use ?

Foued

[Foued_KH]

Hello @SPeri.1​ ,

• FilterActivation specifies if we want to enable Filters or not. Obviously we have to enable them.
• SlaveStartFilterBank specifies How many Filter Banks do we want to assign to CAN1. Basically the controllers with dual CAN peripheral have 28 Filter Banks, which can be distributed between these 2 CAN. Here I am assigning 20 Filter Banks to the CAN1, and Rest to the CAN 2.
  • This parameter is useless for the controllers with single CAN peripheral. And these Controllers have 14 Filter Banks ( 0 to 13)
• FilterBank specifies which Filter Bank do we want to use for the filter Process. Here I have assigned 20 Banks for CAN 1, and I can only choose Out of these 20 Banks. So I am choosing Bank number 18.
  • In case of Single CAN Peripheral, you can choose any value between 0 to 13.

Foued

[SofLit · Accepted solution]

Hello,

You have an issue with filter config:

.SlaveStartFilterBank parameter you have to configure it once and it determines the filter allocation for both CAN1 and CAN2. Assimilate it as a cursor.

.FilterBank should be configured according to .SlaveStartFilterBank.

I'm attaching a text file that explains the principal.

Hope it helps

[SPeri.1]

STM32F105RCT6

[SPeri.1]

Now i get it. Thank you so much.