Comparison between Asynchronous and Synchronous Format.

Subject : Microcontroller and Embedded Programming

Topic : Asynchronous Serial Data Connection

Difficulty : Medium

1 Answer
Asynchronous data transfer Synchronous data transfer
It is used to transfer one character at a time. It is used transfer a block of characters at a time.
Used for data transfer rates < 20 kbits/second. Used for high data transfer rates > 20 kbits/second.
Sync characters are not transmitted along with characters. Sync characters are transmitted along with the group of characters.
Start bit and stop bit for each character is present which forms a frame. No start and stop bit is used.
Two separate clock inputs can be used for transmitter and receiver. One clock is used for both transmitter and receiver.
No synchronization is required hence hardware and software implementation is possible. Since synchronization is involved, this can be implemented by using hardware only.
Speed is less, because overheads are more per byte (start bit, stop bit(s) etc.) Speed is high because overheads are spread over a frame or packet of data bytes.
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