Hi Uwe, I´ve problems with overruns. It seams that static void STMCanRX0Interrupt( void *arg) if (CANBBx[CM3BB_OFFSET(CAN_TypeDef, RF0R,_BI32(CAN_RF0R_FOVR0))]) { CANBBx[CM3BB_OFFSET(CAN_TypeDef, RF0R,_BI32(CAN_RF0R_FOVR0))]=0; ci->can_overruns++; doesn´t reset. Is it possible that we have tto write "1" tot he register to reset? Achim