Analysis of UART Protocol

Analysis of UART Protocol

UART stands for Universal Asynchronous Receiver/Transmitter, which stands for Universal Asynchronous Receiver/Transmitter. In the 1860s, Bell invented the UART protocol to solve the communication problem between computers and teleprintersts, converting parallel input signals into serial output signals. Due to its simple and practical nature, UART has become a widely used communication protocol. The serial ports, RS232, RS485 and other buses that we come into contact with in our daily lives basically use UART protocol internally.

In order to better understand and analyze the relationship between protocols and buses, we usually divide a complete communication specification into physical layer, protocol layer, and application layer. The physical layer only defines the true signal characteristics (such as voltage, current, driving capability, etc.), as well as the correspondence between electrical signals and logical signals 0 and 1; The protocol layer does not care about how to implement the underlying 0s and 1s, but only specifies the protocol specifications and communication processes (such as start, data, and end) for logical signals; The application layer is not concerned with how data is obtained, only defining the meaning of data representation and how to implement specific business logic.

Analysis of UART Protocol

Different physical layer implementations

Due to the fact that the input of the UART protocol layer is a logical 0/1 signal, which can be distinguished by different level standards in the physical layer. Different physical layers can be used to meet different communication needs. For example, in simple onboard communication or common device debugging scenarios, using simple LVTTL/TTL levels can enable UART protocol communication between two devices.