Interpretation of this article: A complete list of interfaces commonly used by engineers

As an engineer, you should often deal with interfaces, so the editor asked Baidu. The complete definition of interface is that an entity provides an abstraction to the outside world to separate the external communication method from the internal operation, so that it can be modified internally without affecting the way other external entities interact with it, just like the multiple abstractions provided by object-oriented programming.

It feels so complicated. In fact, the interface is an indirect means, so compared with direct communication, it will cause some extra burden. In electronic products, there are hardware interfaces and software interfaces: the interface between the hardware components of computers and other information machines is called hardware interface; the interface between the software components of computers and other information machines is called software interface.

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The following is an introduction to this hardware interface:

The main hardware interfaces are:

IDE

The full name of IDE is "Integrated Drive Electronics", which means "electronic integrated drive". Its original meaning refers to a hard disk drive that integrates the "hard disk controller" and the "disk body". Integrating the disk body and the controller reduces the number and length of cables in the hard disk interface, enhances the reliability of data transmission, and makes it easier to manufacture hard disks, because hard disk manufacturers no longer need to worry about whether their hard disks are compatible with controllers produced by other manufacturers. For users, it is also more convenient to install hard disks. The IDE interface technology has been continuously developing since its birth, and its performance has been continuously improved. Its low price and strong compatibility have created a position that other types of hard disks cannot replace.

IDE represents a type of hard disk, but in actual applications, people are also accustomed to using IDE to refer to the earliest IDE type hard disk ATA-1. This type of interface has been eliminated with the development of interface technology, and later developed into more types of hard disk interfaces, such as ATA, Ultra ATA, DMA, Ultra DMA and other interfaces all belong to IDE hard disks.

SCSI

SCSI is short for "Small Computer System Interface", which is a completely different interface from IDE (ATA). IDE is a standard interface for ordinary PCs, but SCSI is not designed specifically for hard disks. It is a high-speed data transmission technology widely used in minicomputers. SCSI interface has the advantages of wide application range, multi-tasking, large bandwidth, low CPU usage, and hot plugging, but its high price makes it difficult to be as popular as IDE hard disks. Therefore, SCSI hard disks are mainly used in mid- and high-end servers and high-end workstations.

Fibre Channel

The English spelling of Fibre Channel is Fibre Channel. Like the SCSI interface, Fibre Channel was not originally developed for hard disks. It was designed specifically for network systems. However, as storage systems demanded speed, it was gradually applied to hard disk systems. Fibre Channel hard disks were developed to improve the speed and flexibility of multi-hard disk storage systems. Its appearance greatly improved the communication speed of multi-hard disk systems. The main features of Fibre Channel are: hot-swappability, high-speed bandwidth, remote connection, and a large number of connected devices.

Fibre Channel is designed for multi-hard disk system environments such as servers. It can meet the high data transmission rate requirements of high-end workstations, servers, massive storage subnets, and peripherals for bidirectional, serial data communications through hubs, switches, and point-to-point connections.

SATA

Hard disks using SATA (Serial ATA) ports are also called serial port hard disks, which are the trend of future PC hard disks. In 2001, the Serial ATA Committee, composed of several major manufacturers such as Intel, APT, Dell, IBM, Seagate, and Maxtor, formally established the Serial ATA 1.0 specification. In 2002, although the related devices of Serial ATA have not yet been officially launched, the Serial ATA Committee has already established the Serial ATA 2.0 specification. Serial ATA uses a serial connection method. The serial ATA bus uses an embedded clock signal and has a stronger error correction capability. Compared with the past, its biggest difference is that it can check the transmission instructions (not just data). If errors are found, they will be automatically corrected, which greatly improves the reliability of data transmission. The serial interface also has the advantages of simple structure and hot plug support. Serial port hard disk is a new type of hard disk interface that is completely different from parallel ATA. It is well-known for using serial data transmission. Compared with parallel ATA, it has many advantages. First of all, Serial ATA transmits data in a continuous serial manner, and only transmits 1 bit of data at a time. This can reduce the number of pins on the SATA interface, reduce the number of connecting cables, and improve efficiency.

RAID Card

Of course, IDE RAID also has its disadvantages. For example, it cannot compare with SCSI RAID in terms of CPU usage and the number of connected devices. At the same time, IDE RAID currently only supports RAID0, RAID1 and RAID0+1, and its performance is slightly inferior to SCSI RAID. Therefore, SCSI RAID is still the main application in high-performance computers. SATA RAID is a newly born RAID method. It is similar to IDE RAID. Its biggest advantage is low cost. Other aspects are also similar to IDE RAID.

It refers to the hard disk interface supported by the RAID card. There are three main types: IDE interface, SCSI interface and SATA interface.

When RAID technology was first introduced, it was based on the SCSI interface. Due to its high cost, it was mainly used for high-end applications such as servers. Ordinary users had no chance to own RAID. With the popularization of computers, PC computers have experienced unprecedented prosperity. Accordingly, driven by the market, the price of IDE interface devices used for PC computers has dropped significantly, while the performance has been greatly improved. In view of this, RAID technology began to be transplanted to the IDE interface, and RAID applications based on the IDE interface were launched, called IDE RAID. RAID applications based on the SCSI interface are correspondingly called SCSI RAID. Compared with SCSI RAID, IDE RAID has a very low price and performance that is not inferior at all. Accordingly, IDE RAID solutions have a high cost-effectiveness that SCSI RAID cannot match. Therefore, since its launch, IDE RAID has been widely welcomed by ordinary PC users and ordinary commercial applications.

MD equipment

MD device interface (called port in Hong Kong and Taiwan) refers to the input and output interfaces of MD (Mini Disc) products. First of all, as an MD product, the headphone output interface is naturally necessary. In addition to the basic headphone output interface, recording and playback products should also have a line input interface, so that the MD can be connected to other playback devices, the played audio can be input into the MD and recorded on the MD disc. NetMD products should also have a USB interface, so that they can be connected to a computer to transfer files. Some products also have a microphone interface, which can record external sounds through the MD.

USB interface

It is a technology developed for transferring data between PC and digital devices. Standard USB, Mini USB (typical application: MP3), Micro USB (typical application: Android smartphone) have become the most common USB interfaces. It is widely used in information communication products such as personal computers and mobile devices, and has been expanded to other related fields such as photographic equipment, digital TV (set-top boxes), game consoles, etc. USB has developed from USB 1.0 to the latest USB 3.1. USB 3.1: The transmission speed is 10Gbit/s, the three-stage voltage is 5V/12V/20V, the maximum power supply is 100W, and the new Type-C plug is no longer divided into positive and negative.

USB Type-C port

The biggest feature of the Type-C double-sided pluggable interface is that it supports double-sided insertion of the USB interface, which officially solves the global problem of "USB can never be inserted correctly". It can be inserted from the front or back. At the same time, the USB data cable used with it must also be thinner and lighter. Type-C PD chip manufacturers include: Microchip, Cypress, NXP, ROHM, Tech-Lead Semiconductor, Power Integrations, etc.

The following are commonly used interfaces:

(1) Infrared interface: It is a cheap, short-distance, wire-free, low-power and highly confidential communication solution. It is mainly used in wireless data transmission in PCs, but has gradually begun to be used in wireless network access and short-distance remote control of home appliances. In view of the many benefits of infrared communication, almost all motherboards now provide infrared interfaces so that users can use them to communicate with devices with infrared interfaces, such as laptops, printers, modems, PDAs, mobile phones, etc. However, the computer motherboard only provides an infrared interface and does not provide a complete transmitting and receiving device, so when users want to use infrared communication, they still need to purchase an infrared connector.

(2) DB interface: D-type data interface, an interface standard used to connect electronic devices (such as computers and peripherals). It is named D-type interface because its shape is similar to the English letter D.

(3) PCI interface: It is the most widely used interface in personal computers. Almost all motherboards have this type of slot. PCI slots are also the type of slots with the largest number on motherboards. On the currently popular desktop motherboards, ATX motherboards generally have 5 to 6 PCI slots, while smaller MATX motherboards also have 2 to 3 PCI slots, which shows its wide application.

(4) Serial interface: Serial interface (Serial port) is also called "serial port" or serial communication interface (usually refers to COM interface). It is an expansion interface that uses serial communication. Common ones include RS-232 (using 25-pin or 9-pin connector) for general computer applications and half-duplex RS-485 and full-duplex RS-422 for industrial computer applications.

RS-232 is one of the mainstream serial communication interfaces now. The full name of the RS-422 interface standard is "Electrical Characteristics of Balanced Voltage Digital Interface Circuits", which defines the characteristics of the interface circuit. The typical RS-422 is a four-wire interface. In fact, there is also a signal ground wire, a total of 5 wires. Its DB9 connector pin definition. The RS-485 interface is developed based on RS-422, so many electrical regulations of RS-485 are similar to RS-422.

(5) PS/2 interface: The PS/2 interface is a 6-pin circular interface with 2 pins unused. PS/2 is one of the common interfaces on earlier computers, used for devices such as mice and keyboards. Generally, the mouse of the PS/2 interface is green and the keyboard is purple. The PS/2 interface is an input device interface, not a transmission interface. Therefore, the PS2 port has no concept of transmission rate, only scanning rate.

(6) Dock interface (typical application: Apple products): There are 9-pin and 30-pin Dock interfaces. Apple began using the 30-pin dedicated Dock interface with the iPod 10 years ago, and almost all data synchronization and peripherals rely on this interface. Since Apple launched the 9-pin Lightning Dock interface when the iPhone 5 was released, the release of the new interface standard also means that the 30-pin Dock interface that Apple has used for 9 years will be officially replaced.

(7) RJ11 interface (typical application: telephone): A typical Internet phone will provide two RJ-11 interfaces. One RJ-11 interface is used to connect to the telephone line connected to the HomePNA switch, and the other RJ-11 interface is connected to the telephone.

(8) RJ45 interface (typical application: network cable): RJ45 interface is usually used for data transmission, and the most common application is the network card interface.

(9) Radio frequency interface (TV interface): TV interface is also called RF radio frequency input interface. The antenna and analog closed-circuit TV are connected using the radio frequency (RF) interface. As the most common video connection method,

It can transmit analog video and audio signals at the same time. The RF interface transmits the mixed encoded signal of video and audio. The circuit of the display device performs a series of separation and decoding on the mixed encoded signal before outputting the image. Since the mixed encoding of video and audio is required, the signals will interfere with each other, so its image output quality is the worst among all interfaces. Cable TV and satellite TV receiving equipment also often use RF connection, but in this case, they transmit digital signals.

(10) AV interface: The AV interface separates the video and audio for transmission, thus avoiding mutual interference between the audio and video. However, since the brightness and color need to be decoded and displayed during video transmission, there is still loss in video transmission, so current high-definition video playback has basically abandoned the AV interface.

(11) DIN interface: The S terminal is also called mini-DIN interface in some projector manufacturers. Different products including 4-core (without sound output), 5-core, 6-core, 7-core, 8-core, and 9-core (can provide 6-channel signal output) are used on projectors.

(12) VGA interface: The VGA terminal V (other names include RGB terminal, D-sub 15, or mini D15) on a laptop is a 3-row 15-pin DE-15. VGA terminals are usually found on computer graphics cards, monitors, and other devices. They are used to transmit analog signals.

(13) DVI interface: Digital Video Interface. A technology for high-speed transmission of digital signals invented by the Digital Display Working Group (DDWG) established at the Intel Developer Forum in September 1998. There are three different interface forms: DVI-A, DVI-D and DVI-I. DVI-D has only a digital interface, while DVI-I has both digital and analog interfaces. Currently, DVI-i (24+5) is the main application.

(14) HDMI interface: High Definition Multimedia Interface is a digital video/audio interface technology. It is a dedicated digital interface suitable for image transmission. It can transmit audio and image signals simultaneously, with a maximum data transmission speed of 2.25GB/s.

(15) BNC interface: BNC, the full name is Bayonet Nut Connector (the name vividly describes the appearance of this connector), also known as British Naval Connector (British Navy Connector, which may be the first connector used by the British Navy) or Bayonet Neill Conselman (Neill Conselman bayonet, this connector was invented by a man named Neill Conselman).

(16) RCA analog audio: RCA connector is commonly known as lotus head. Using RCA cable to transmit analog signals is currently the most common audio connection method. Each RCA cable is responsible for transmitting the audio signal of one channel, so a pair of cables is required for stereo signals. For multi-channel systems, the same number of cables should be used according to the actual number of channels. For stereo RCA audio interfaces, the right channel is usually marked in red, and the left channel is marked in blue or white.

(17) S/PDIF interface: S/PDIF stands for Sony/Philips Digital Interconnect Format, a civilian digital audio interface protocol developed by Sony and Philips. Due to its widespread adoption, it has become the de facto civilian digital audio format standard. A large number of consumer audio digital products such as civilian CD players, DAT, MD players, and computer sound card digital ports all support S/PDIF. Many professional devices also have interfaces of this standard.

(18) XLR interface: XLR is commonly known as the XLR connector, which consists of a three-pin plug and a locking device. Due to the use of a locking device, the XLR connection is quite reliable. The large three-core interface uses a plug with a diameter of 6.35 mm. Its advantage is that it is wear-resistant and suitable for repeated plugging and unplugging. Balanced analog audio connections are mainly found in high-end analog audio equipment or professional audio equipment.

(19) SM card interface: SM card stands for Smart Media, which was launched by Toshiba in 1995. SM card itself has no control circuit, so it is smaller in size. Many older cameras use SM memory cards. Since its control circuit is designed in digital devices, compatibility issues are prominent. It is gradually being eliminated.

(20) MMC card interface: MMC card stands for MultiMedia Card. It was launched by SanDisk and Siemens in 1997 and can be found in all kinds of portable devices. Later upgraded versions include RS-MMC (Reduced Size MMC), MMC Micro card (Samsung standard, 10-pin, for personal use), etc. It is said that there are also High-Speed ​​MMC, MMCplus and MMCMobile.

(21) SD card interface: SD card stands for Secure Digital Memory Card, which was launched in 1999 by Toshiba, Panasonic and SanDisk. It has high capacity, high data transfer rate and write protection. Pin 9PIN. The SD card specification is developed from MMC. The size is similar to MMC. SD card and MMC card are upward compatible. SD card retains the 7-pin pin of MMC and expands the 2-pin data line. SD card also has two types: low speed and high speed. High speed SD card is also called SDHC. Currently, 4G SD cards are basically SDHC.

(22) XD card interface: The full name of the XD card is XD-Picture Card. XD is also the abbreviation of Extreme Digital. It was jointly launched by Fujifilm and Olympus and is specially designed for digital cameras. It has 18 pins on one side. The theoretical maximum capacity of the XD card can reach 8GB, which has a lot of room for expansion. Currently, the XD cards on the market have different capacity specifications such as 16/32/64/128/256MB. The picture below is an Olympus 1G XD card with a clear XD logo in the middle.