Understanding of UART FIFO-EEWORLD

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Necessity of FIFO. When performing UART communication, the interrupt method is simpler and more efficient than the polling method. However, if there is no transceiver FIFO, each data (5 to 8 bits) transmitted must be interrupted and processed once, and the efficiency is still not high. If there is a transceiver FIFO, an interrupt can be generated only after a number of data (up to 14) are continuously sent and received, and then processed together. This greatly improves the efficiency of transceiver.

　　Receive timeout problem. If there is no receive timeout function, the interrupt will not be triggered when the other party has finished sending but the receive FIFO is not full (the interrupt will be triggered only when the FIFO is full), resulting in the problem that the valid data received at the end cannot be processed. With the receive timeout function, if the receive FIFO is not full and the other party has stopped sending, the timeout interrupt will be triggered within the reception time of no more than 3 data, so the data will be processed as usual.

　　When sending, as long as the send FIFO is not full, the data is continuously put in, and the send subroutine is directly exited after it is put in. Then, when the FIFO is actually sent, an interrupt will be automatically generated to notify the main program: I have completed the real sending.

　　When receiving, if the other party sends continuously, after the FIFO is filled, it will notify the main program in an interrupt manner and say: Now a batch of data has arrived, please process it.

　　It doesn't matter if the other party sends intermittently. When the interval is too long (2 to 3 character transmission time), an interrupt will occur. This time it is a timeout interrupt, which notifies the main program that the other party may have completed sending, but the FIFO is not full, so please handle it.

Keywords：UART FIFO Reference address：Understanding of UART FIFO

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