What is USB, USB 2.0 and 3.0 difference, joinwinchips science and technology

Universal Serial Bus (USB) is an industry standard that specifies the physical interfaces and protocols for connecting, data transferring and powering of hosts, such as personal computers, peripherals, e.g. keyboards and mobile devices, and intermediate hubs. USB was designed to standardize the connection of peripherals to computers, replacing various interfaces such as serial ports, parallel ports, game ports, and ADB ports.It has become commonplace on a wide range of devices, such as keyboards, mice, cameras, printers, scanners, flash drives, smartphones, game consoles, and power banks.

As of 2023, USB consists of four generations of specifications: USB 1.‘‘x’’, USB 2.0, USB 3.‘‘x’’, and USB4. Since USB4 the specification enhances the data transfer and power supply functionality with

Each specification subversion supports different maximum signaling rates from 1.5 Mbit/s in USB 1.0 to 80 Gbit/s in USB4.USB also provides power supply to peripheral devices; the latest versions of the standard extend the power delivery limits for battery charging and devices requiring up to 240 watts (USB Power Delivery (USB-PD)).Over the years USB(-PD) has been adopted as the standard power supply and charging format for many mobile devices, such as mobile phones, reducing the need for proprietary chargers.

USB connector interfaces are classified into three types: A (host), B (peripheral), and C (2014, replaces A and B). The A and B types know different sizes: Standard, Mini, and Micro. The standard size is the largest and is mainly used for desktop and larger peripheral equipment. The mini size was introduced for mobile devices, but it was replaced by the thinner micro size. The micro size is nowadays the most common for smartphones and tablets. The USB Type-C connector interface is the newest and the only one applicable to USB4. It is reversible and can support various functionalities and protocols; some are mandatory, many just optional, and depending on the type of the device: host, peripheral device, or hub.

Since the USB 1.1 specification fully replaces the USB 1.0 specification, and since the USB 3.2 specification fully replaces the USB 3.1 (and therefore the USB 3.0 specification as well), and since USB 2.0 is backward-compatible with USB 1.0/1.1, and since the USB 3.x specifications include the USB 2.0 specification, and since USB4 "functionally replaces" the USB 3.2 specification "while retaining USB 2.0 bus operating in parallel", backward-compatibility is always given, but obviously always comes along with a decrease in, both, signaling rates and power rates, and less supported functionalities.

The USB 3.0 specification defined a new architecture and protocol, named SuperSpeed (aka SuperSpeed USB, marketed as SS), which included a new lane for a new signal coding scheme (8b/10b symbols, 5 Gbps; also known as Gen 1) providing full-duplex data transfers that physically required five additional wires and pins, while preserving the USB 2.0-architectur and -protocols and therefore keeping the original 4 pins/wires for the USB 2.0 backward-compatibility resulting in 9 wires (with 9 or 10 pins at connector interfaces; ID-pin is not wired) in total. The USB 3.1 specification introduced an Enhanced SuperSpeed-architecture – while preserving the SuperSpeed-architecture and -protocol – with an additional SuperSpeedPlus-architecture adding a new coding schema (128b/132b symbols, 10 Gbps; also known as Gen 2) and protocol named SuperSpeedPlus (aka SuperSpeedPlus USB, for some time period marketed as SS+). The USB 3.2 specification even added an additional second lane to the Enhanced SuperSpeed-architecture besides other enhancements, so that SuperSpeedPlus USB implements the Gen 1x2, Gen 2x1 and Gen 2x2 operation modes. The SuperSpeed-architecture and -protocol (aka SuperSpeed USB) still implements the one-lane Gen 1x1 operation mode. Therefore, two-lane operations, namely USB 3.2 Gen 1x2 (10 Gbit/s) and Gen 2x2 (20 Gbit/s), are only possible with Full-Featured USB Type-C fabrics (24 pins).As of 2023, they are hardly yet implemented by most products so far. On the other hand, USB 3.2 Gen 1(x1) (5 Gbit/s) and Gen 2(x1) (10 Gbit/s) implementations are quite common now for some years.

USB 3.0 transfer rates are up to ten times that of USB 2.0, which has a rate of 480 Mbps, while USB 3.0 can reach up to 4.8 Gbps. Of course, many devices don't need such a high rate, but devices such as hard drives and card readers still require high speeds. Compared to USB 2.0, USB 3.0 will be more energy efficient. In addition, USB 3.0 is backward compatible and supports USB 2.0 devices.

USB 3.0 has standards compatible with older versions, interfaces that support universal I/O, and will be optimised to reduce energy consumption while improving protocol efficiency for products in the areas of computers, consumer products, and mobile products, products that support fast synchronous mobility, the ability to support both optical and digital component specifications, and the ease of use and plug-and-play characteristics of legacy USB technology. mini USB 3.0 has interfaces that Will be divided into A, B two kinds of male port (Plug), while the female port (Receptacle) will have B and AB two kinds of, from the shape, AB female port can be compatible with A and B two kinds of male port, at the same time you can see, 3.0 version of the male port of the pins is 9 pins, while 2.0 is 5 pins. In order to be backward compatible with version 2.0, USB 3.0 uses a 9-pin design, four of which are identical to the shape and definition of USB 2.0, while the other five are specifically for USB 3.0.
A lot of people who are relatively new to USB 3.0 are worried about not knowing how to identify and distinguish between USB 2.0 interface and USB 3.0 interface, so let's look at the difference by comparing the two.

USB 3.0 standard A-type interface is backward compatible with USB 2.0/1.1, its size is the same, but the two interfaces are still very good to distinguish:
Observe the colour method, in order to make a distinction with USB 2.0, USB 3.0 Primoter Group recommends the industry to use blue base in USB 3.0 interface, so we can distinguish it from the colour.
Observe the contact plate method, this way is more cautious, USB 2.0 only has 4pin metal contact plate, while USB 3.0 is 9pin contact plate, the front 4pin and USB 2.0 is one to one, the rear 5pin is exclusive for USB 3.0.
As for the USB 3.0 B-type interface is better distinguished, USB 3.0 standard B-type interface size is larger than USB 2.0, the upper part of the more prominent, to accommodate the new 5pin contact piece.
Observe the logo method, USB 3.0 logo as shown below, "SS" stands for "SuperSpeed", in the USB 3.0 interface part will have the logo. The USB 3.0 cable is also slightly thicker than the USB 2.0 cable due to the additional routing.

USB interface can be universal, but the speed has been the slowest prevail. That is, USB2.0 devices and USB3.0 connection, the speed has been USB2.0 at the same time USB3.0 can provide faster charging speed, than USB2.0 about eighty per cent faster.