Serial interface is referred to as serial port, also known as serial communication interface or serial communication interface (usually referred to as COM interface), which is an expansion interface using serial communication. Serial Interface (SerialInterface) Introduction to the knowledge of serial ports and parallel ports on the electronic connection system (Figure 1) refers to the sequential transmission of data bit by bit, which is characterized by simple communication lines, as long as a pair of transmission lines can realize two-way communication (you can directly Using telephone lines as transmission lines), which greatly reduces the cost, especially suitable for long-distance communication, but the transmission speed is slow.
Serial port division standard:
Synchronous Serial Interface (English: SynchronousSerialInterface, SSI) is a commonly used industrial communication interface.
Asynchronous serial refers to UART (UniversalAsynchronousReceiver/Transmitter), Universal Asynchronous Receive/Transmit. UART is a chip whose parallel input becomes serial output, usually integrated on the motherboard. UART includes TTL level serial port and RS232 level serial port. TTL level is 3.3V, while RS232 is negative logic level, it defines +5~+12V as low level, and -12~-5V as high level, MDS2710, MDSSD4, EL805, etc. are RS232 interfaces, EL806 Has TTL interface.
The interface characteristics of a parallel interface can be described from two aspects:
1. The width of the data channel transmitted in parallel, also known as the number of bits transmitted by the interface;
2. The characteristic of additional interface control lines or interactive signals used to coordinate parallel data transmission. The width of the data can be from 1 to 128 bits or wider, and the most commonly used is 8 bits, which can transmit 8 data bits at a time through the interface. The most commonly used parallel interface in the computer field is the so-called LPT interface.
The main features of the parallel port:
The parallel interface means that all bits of data are transmitted at the same time, which is characterized by fast transmission speed, but when the transmission distance is long and the number of bits is large, the communication line is complicated and the cost is increased.
The difference between serial port and parallel port
The serial port is described as one lane, and the parallel port has 8 lanes that can transmit 8-bit (one byte) data at the same time. But it does not mean that the parallel port is fast. Due to the mutual interference (crosstalk) between the 8-bit channels, the transmission speed is limited, and the transmission is prone to errors. The serial ports do not interfere with each other. The parallel port can send a large amount of data at the same time, but it is slower than the serial port. This is how serial hard disks are valued by people.