Only a single CAN filter can be used with STM32F4xx devices

Mbed OS Bugs
1

With commit F1D10CF the complete can_api.c file has been replaced with one that is targeted for the F7 family. With this implementation, the can_filter function ignores the handle argument and uses a fixed filter index of zero and calls HAL_FDCAN_ConfigFilter. The earlier implementation uses the handle argument as the filter index and calls HAL_CAN_ConfigFilter.

The consequence is that now only a single CAN message filter can be set (and probably only for CAN1!).

2

Hi

Is this commit

solves your issue ?

Jerome

3

Hi Jerome,

That commit does not solve my problem.

To regain the ability to use multiple CAN filters I derived my own class from mbed::CAN and re-implemented the filter member function with the code from the git commit for issue #5791 ( STM32 CAN: fix wrong ID and MASK filter).

class RawCAN : public mbed::CAN
{
    public:
        RawCAN( PinName rd, PinName td )
            : CAN( rd, td )
        {}
        RawCAN( PinName rd, PinName td, int hz )
            : CAN( rd, td, hz )
        {}
        virtual void lock  () { /*do nothing*/ }
        virtual void unlock() { /*do nothing*/ }

        int filter( uint32_t id, uint32_t mask, CANFormat format, int32_t handle )
        {
            int retval = 0;

            // filter for CANAny format cannot be configured for STM32
            if ( (format == CANStandard) || (format == CANExtended) )
            {
                CAN_FilterConfTypeDef  sFilterConfig;
                sFilterConfig.FilterNumber = handle;
                sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
                sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;

                if (format == CANStandard)
                {
                    sFilterConfig.FilterIdHigh = id << 5;
                    sFilterConfig.FilterIdLow =  0x0;
                    sFilterConfig.FilterMaskIdHigh = mask << 5;
                    sFilterConfig.FilterMaskIdLow = 0x0; // allows both remote and data frames
                }
                else
                { // format == CANExtended
                    sFilterConfig.FilterIdHigh = id >> 13; // EXTID[28:13]
                    sFilterConfig.FilterIdLow = (0xFFFF & (id << 3)) | (1 << 2); // EXTID[12:0] + IDE
                    sFilterConfig.FilterMaskIdHigh = mask >> 13;
                    sFilterConfig.FilterMaskIdLow = (0xFFFF & (mask << 3)) | (1 << 2);
                }

                sFilterConfig.FilterFIFOAssignment = 0;
                sFilterConfig.FilterActivation = ENABLE;
                sFilterConfig.BankNumber = 14 + handle;

                HAL_CAN_ConfigFilter( &_can.CanHandle, &sFilterConfig );
                retval = handle;
            }
            return retval;
        }

};

Antoon

4

Hi
If you find the correction in mbed-os code, push a pull request,
we will be happy to review it and merge it!
Thx