I want to know more about USART operation and I will appreciate for your comment and explanations.
1)If RXNE=1 and it execute interrupt subroutine always it means that we a valid data? even the between operation something occurs and or we have a connection lost?
2)what does Noise flag exactly do?(In the 3-bit sampling if one of samples fails we should ignore the received data)?
3)In receiving mode if something happens that one of error flag is set(for example I lost my connection during receiving(I remove Rx line) ) and after that the next character is sent (Or I connect the RX wire again)what does the MCU work? it receives the next character or do something else?
4)if I don't read the one of received bytes and overrun error occurs (even the interrupt flag of RXNE has been activated), what is the reaction of MCU?