As one of computer communication modes, serial communication mainly plays the role of data transmission between host and peripherals as well as between hosts. Serial communication is characterized by few transmission lines and low cost. It is suitable for the communication of short-distance Human Machine Interface, real-time monitoring and other systems. With the help of the existing telephone network, long-distance transmission can also be realized. Therefore, serial communication interface is a common interface in computer system.
Serial communication technology refers to a mode of communication in which both sides of communication proceed in bitwise and follow the time sequence. In serial communication, the data is transmitted in sequence by bit, and each bit takes up a fixed time length. The information exchange between systems can be completed by using a few communication lines, which is especially suitable for long-distance communication between computers and computers and between computers and peripherals. Serial communication is mainly used for serial data transmission between systems (multi-master control system), equipment (master control equipment and auxiliary equipment) and devices (master control CPU and functional chip), so as to realize data transmission and sharing.
The serial bus communication process is characterized by fewer communication lines, simple wiring, convenient construction, flexible structure, inter-system negotiation protocol, high degree of freedom and flexibility, so it is applied more and more in electronic circuit design, information transfer and other aspects.
Serial communication refers to the serial data transmission between the computer host and peripherals and between the host and the hosts. Using one data line, the data is transmitted one bit at a time, and each bit occupies a fixed length of time. It only needs a few lines to exchange information between systems, especially suitable for long-distance communication between computers and computers and between computers and peripherals.
Synchronous communication is a communication mode in which data is transmitted sequentially and only one frame of information is transmitted at a time. The information frame here differs from the character frame in asynchronous communication and usually contains several data characters.
In asynchronous communication, there are two important indicators: character frame format and baud rate. Data is usually transmitted as character frames in units of characters or bytes. Character frames are sent frame by frame by sender and received frame by receiver through transmission line. The sender end and receivier end can control the sending and receiving of data by their own clocks. The two clock sources are independent from each other and do not synchronize with each other.
The communication method in which data is transmitted in sequence on a single bit-wide transmission line one bit after another is called serial communication. In parallel communication, a byte (8 bits) of data is transmitted from source to destination simultaneously on 8 parallel transmission lines. In serial communication, data is transmitted bit by bit on a single bit-wide transmission line. Such a byte of data is sent eight times in sequence from low to high. It can be seen that the characteristics of serial communication are as follows:
1. Save transmission lines, and this is obvious. This feature is especially important in remote communication. It is also the main advantage of serial communication.
2. Low data transmission efficiency. Compared with parallel communication, this is also obvious. It is also the main disadvantage of serial communication.
For example: transfer one byte, if the time required for parallel communication is 1T, then the time required for serial communication is at least 8T. Thus, serial communication is suitable for long-distance transmission and can range from a few meters to thousands of kilometers. For long distance, low speed communications, serial communication is often the only option. Parallel communication is suitable for short distance, high rate data transmission, usually transmission distance less than 30 meters.