CAN Filter on STM32F3

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CAN Filter on STM32F3

Topic last updated 05 Feb 2018, by Jerome Coutant. 2 replies

# 11 Mar 2017

Hello,
it is good to see that the CAN bus support is now included in mbed for STM32 and is seems to be working fine (on an STM32F303K8).
However, trying to set a reception filter did not work as I expected, so I changed the can_filter function in can_api.c to make it work for me.
Cheers,
Max

Changes to can_api.c

int can_filter(can_t *obj, uint32_t id, uint32_t mask, CANFormat format, int32_t handle)
{
    CanHandle.Instance = (CAN_TypeDef *)(obj->can);
    CAN_FilterConfTypeDef  sFilterConfig;

    sFilterConfig.FilterNumber = handle;
    sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
    sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
    sFilterConfig.FilterFIFOAssignment = 0;
    sFilterConfig.FilterActivation = ENABLE;
    sFilterConfig.BankNumber = 14 + handle;
    switch (format) {
        case CANStandard:
            sFilterConfig.FilterIdHigh = (uint16_t) (id << 5);
            sFilterConfig.FilterIdLow = 0;
            sFilterConfig.FilterMaskIdHigh = (uint16_t) (mask << 5);
            sFilterConfig.FilterMaskIdLow = CAN_ID_EXT;
            break;
        case CANExtended:
            sFilterConfig.FilterIdLow = (uint16_t) (id << 3);
            sFilterConfig.FilterIdLow |= CAN_ID_EXT;
            sFilterConfig.FilterIdHigh = (uint16_t) (id >> 13);
            sFilterConfig.FilterMaskIdLow = (uint16_t) (mask << 3);
            sFilterConfig.FilterMaskIdLow |= CAN_ID_EXT;
            sFilterConfig.FilterMaskIdHigh = (uint16_t) (mask >> 13);
            break;
    }

    HAL_CAN_ConfigFilter(&CanHandle, &sFilterConfig);

    return 0;
}