[Internet of Things Communication Technology] - USB

Overview

When it comes to communication interfaces, especially wired ones, USB is ubiquitous in our lives. The USB (Universal Serial Bus) has gradually replaced other interface standards for data communication (refer to the various peripheral interfaces on the computer in the image below—mouse, keyboard, monitor, printer, hard drive, etc.). This technology is highly successful. USB uses a 4-pin (9-pin for the USB 3.0 standard) plug as the standard connector, allowing all peripherals to be connected in a daisy-chain configuration, supporting up to 127 external devices without bandwidth loss. USB ports and cables are used to connect hardware such as printers, scanners, keyboards, mice, flash drives, external hard drives, joysticks, cameras, and monitors to various computers, including desktops, tablets, laptops, netbooks, and other devices. Therefore, it can be said that USB refers to the type of cables and connectors used to connect a wide range of external devices to computers.

History

USB was developed collaboratively by Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel. The USB standard is maintained by the USB Implementers Forum (USB-IF).

Before the invention of USB, devices were connected to computers via serial or parallel ports. In addition to communication, USB can also be used for charging. The mobile phones or tablets we use are charged via USB ports. USB has changed the history of computer connectivity and handheld devices.

• 1996: Initial version, data transfer speed 1.56 Mbits/s, power delivery rate 100mA, connector types: TYPE-A and TYPE-B.
• 1998: USB 1.1 version, data transfer speed 12 Mbits/s, power delivery rate 100mA.
• 2000: USB 2.0 version, data transfer speed 480 Mbits/s, power delivery rate 500mA, connector types: Mini-A, Mini-B, Mini-AB.
• 2007: USB Micro USB On-The-Go, data transfer speed 480 Mbits/s, power delivery rate 500mA, connector types: Micro-A, Micro-B, Micro-AB.
• 2008: USB 3.0 version, data transfer speed 5 Gbits/s, power delivery rate 900mA, connector types: SS series Type A, B, and SS Micro A, B, AB series.
• 2013: USB 3.1 version, data transfer speed 10 Gbits/s, power delivery rate 1.5A.
• 2014: USB Type-C, data transfer speed 10 Gbits/s, power delivery rate 3A. Connector type: Type-C.
• 2017: USB 3.2 version, data transfer speed 20 Gbits/s, power delivery rate 5A.
• 2019: USB4 version, data transfer speed 40 Gbits/s, power delivery rate 5A.

USB Versions

• USB 1.1: USB 1.1 devices can achieve a maximum transfer rate of 12 Mbps, known as Full-Speed USB.
• USB 2.0: Devices compliant with the USB 2.0 standard can achieve a maximum transfer rate of 480 Mbps, known as High-Speed USB.
• USB 3.2 Gen 1: Previously known as USB 3.0, compatible hardware can achieve a maximum transfer rate of 5 Gbps (5,120 Mbps), known as SuperSpeed USB.
• USB 3.2 Gen 2: Previously known as USB 3.1, compatible devices can transfer data at 10 Gbps (10,240 Mbps), known as SuperSpeed+.
• USB 3.2 Gen 2×2: Also known as USB 3.2, compatible devices can transfer data at 20 Gbps (20,480 Mbps), known as SuperSpeed+ USB Dual-Channel.
• USB4: Based on the Thunderbolt 3 specification, USB4 supports 40 Gbps (40,960 Mbps).

USB Connectors

• USB Type-C: Commonly referred to as USB-C, these plugs and sockets are rectangular with four rounded corners. There are only USB 3.1 Type-C plugs and sockets (and cables), but adapters are available for backward compatibility with USB 3.0 and 2.0 connectors. This latest USB connector finally solves the orientation issue. Its symmetrical design allows it to be inserted into a socket either way, so you never have to try again (one of the biggest annoyances with earlier USB plugs). These are being widely adopted on smartphones and other devices.
• USB Type-A: Formally known as USB Standard-A, these plugs and sockets are rectangular and are the most common USB connectors. USB 1.1 Type-A, USB 2.0 Type-A, and USB 3.0 Type-A plugs and sockets are physically compatible.
• USB Type-B: Formally known as USB Standard-B, these plugs and sockets are square with an extra notch on top, most noticeable on USB 3.0 Type-B connectors. USB 1.1 Type-B and USB 2.0 Type-B plugs are physically compatible with USB 3.0 Type-B sockets, but USB 3.0 Type-B plugs are not compatible with USB 2.0 Type-B or USB 1.1 Type-B sockets.
• The USB Powered-B connector is also specified in the USB 3.0 standard. This socket is physically compatible with USB 1.1 and USB 2.0 Standard-B plugs, and of course, with USB 3.0 Standard-B and Powered-B plugs.
• USB Micro-A: The USB 3.0 Micro-A plug looks like two different rectangular plugs fused together, one slightly longer than the other. The USB 3.0 Micro-A plug is only compatible with USB 3.0 Micro-AB sockets.
• The USB 2.0 Micro-A plug is very small and rectangular, resembling a shrunken USB Type-A plug in many ways. The USB Micro-A plug is physically compatible with USB 2.0 and USB 3.0 Micro-AB sockets.
• USB Micro-B: The USB 3.0 Micro-B plug looks almost identical to the USB 3.0 Micro-A plug, as they appear as two separate but connected plugs. The USB 3.0 Micro-B plug is compatible with USB 3.0 Micro-B sockets and USB 3.0 Micro-AB sockets.
• The USB 2.0 Micro-B plug is very small and rectangular, but two corners on one long side are beveled. The USB Micro-B plug is physically compatible with USB 2.0 Micro-B and Micro-AB sockets, as well as USB 3.0 Micro-B and Micro-AB sockets.
• USB Mini-A: The USB 2.0 Mini-A plug is rectangular but with one side more rounded. The USB Mini-A plug is only compatible with USB Mini-AB sockets. There is no USB 3.0 Mini-A connector.
• USB Mini-B: The USB 2.0 Mini-B plug is rectangular with a small indentation on both sides, almost looking like a protruding piece of bread when viewed from the front. The USB Mini-B plug is physically compatible with USB 2.0 Mini-B and Mini-AB sockets. There is no USB 3.0 Mini-B connector.