The Universal Serial Bus (USB) has established itself as the standard interface for PC hardware and increasingly also for entertainment electronics. With the new 3.1er standard some improvements come.
When USB 1.0 was introduced in 1996, there was the first opportunity to connect tens of devices, such as scanners, printers and hard disks, to the desktop PC via a standard interface, without installing an expensive SCSI card that was then expensive to buy. Thanks to the Universal Serial Bus, this is hardly necessary today. USB 1.0 offered a data rate of up to 1.5 MB per second (full speed). However, this was sufficient for mice, keyboards, printers or scanners.
It followed four years later USB 2.0 with 60 MB (Hi-Speed) and in 2008 the USB 3.0 standard with 500 MB per second (Super Speed) was introduced. The USB Promoter Group presented the future USB standard 3.1 at the CES 2013 in Las Vegas: The improved interface of SuperSpeed USB provides data transmissions with up to 10 gigabits per second. However, the actual data rates that can be achieved are significantly lower for all USB standards. For example, external USB 3.0 hard disks barely exceed 100 MB per second.
With the introduction of USB, the interplay of PCs, storage media and peripherals has been significantly simplified. In the meantime, USB ports have long since left the IT and can be found, among other things, on DSL and WLAN routers, TVs, media players, autoradios and game consoles, as well as on control systems for electricity and heating as well as in the car (see devices with USB connection). So, a variety of devices can be connected, including memory sticks, external hard drives, keyboards, mice, scanners, printers and numerous gadgets such as small fans, vacuum cleaners, heated coffee cups and much more besides (see USB gadgets) USB connection.
USB interfaces and USB sticks
The different connectors and cables for USB connections
The good thing in advance: The USB standards 1.0 to 3.0 are compatible with each other. USB 2.0 devices can be connected to USB 3.0 jacks. Specifically: An external hard drive with a USB 2.0 port can be connected to a PC or notebook with a USB 3.0 interface. At the speed, USB 3.0 is the same as USB 2.0 after the weakest link in the chain. Due to the additional contacts, USB 2.0 jacks do not accept USB 3.0 connectors. A USB stick according to the 3er standard fits also in a 2er-Port.
USB cable: The cables for the USB standards 1 and 2 have at one end the flat plug type A, which leads to the PC. At the other end, you can use a Type B male connector that you connect to a printer or scanner, for example.
The type B connector for USB 3.0 devices is split. Then there are the small Mini-B connectors, which are used for external 2.5-inch hard drives. The Micro-B connector is a little flatter, the corresponding socket is usually in smartphones, tablets, cameras or other small devices. The USB 3.0 version of Micro B is slightly wider and has a notch in the guide plate. USB 3.0 plugs and sockets are usually blue colored in the inner part, while in USB 2.0 it is black or white. For the USB Type-C or USB 3.1, there are new cables, plugs and devices: The new connector for USB Type-C has the size of a USB 2.0 Micro-B connector.
More importantly, the annoying rum fumble when connecting USB devices will be a thing of the past. Because with the new plugs it does not matter, how to put them in the connection. And also on both sides of the cable is the same plug. Apple had made this with his Lightning port, which has been used since the iPad 4 and the iPhone 5.
Over time, the new cables will also make the use of power supplies for laptops and smaller devices unnecessary. Because USB Type-C also transmits up to 100 watts of current. USB Type-C is backwards compatible, but adapters are required for existing USB ports.
The cable length: It is limited to five meters with USB 2.0. In the USB 3.0 specification, instead of the length, electrical parameters are specified that the cables must meet. Three meters are possible, with more good shielding also more. However, cables are also sold which do not meet the requirements. For disconnections, try using another USB cable.
Operation and power supply for devices with USB 3.0
Normally the polling procedure is used for USB connections. The host regularly asks all connected peripheral devices if they have data to transfer. However, this query takes time unnecessarily. In the case of USB 3.0, the devices can prevent polling by reporting NRDY (“Not Ready”) on their own. If a device has to transfer data later, it signals ERDY (“Endpoint Ready”) to start the transfer. The separate transmit and receive lines SSTX +/- and SSRX +/- do not have to wait for the bus allocation from the host.
Devices that have sent the NRDY status can go into a power saving mode. Because, in addition to the active connection U0, the USB 3.0 devices know three other modes: With U1, the transmit and receive circuit switches off. At U2, the clock circuit is also interrupted. U3 puts the device into standby mode (Suspend mode). If all devices are in power-saving mode, the host can also shut down its upstream link.
A more common source of problems is the power supply via USB. On the USB 2.0 port, devices are allowed to supply a maximum of 500 milliamps, while for USB 3.0, they are 900 milliamps. The starting current, but also the power requirement during operation, can be more than 500 milliampere on some USB hard disks. These are not recognized by the operating system, or are later reissued. In this case, you should connect the disk to a USB 3.0 port, if it is available, or connect an additional power supply through a USB twisted pair cable (Y cable), which is available for a few dollars on the market.
The latter is however actually not allowed according to the official USB standard, but it mostly works nevertheless. An improvement can also be an active USB hub with its own power supply, which also allows the simultaneous connection of several USB devices.
This makes your USB stick hunt for viruses
The Socket What is charging faster?
A charging adapter can be used to charge a smartphone at the wall outlet. Alternatively simply plug your device into the USB port of your PC and charge it. However, there are some significant differences. If you are in a hurry, always charge your smartphone at the wall outlet. On average, you charge your device three times as fast as the power from the outlet, as when charging via the USB port of the computer. So it takes with our test device, the Samsung Galaxy S4 mini, 3:01 hours, until a 60% load is reached. The same charge reaches the Mini via the socket in 1:15 hours.
Slow charging at the USB port: Since a USB 2.0 port delivers a maximum of 500 mA, charging the connected smartphone takes a long time because the capacity of the current smartphone batteries is very high. With USB 3.0, the current was increased to 900 mA, which allows you to charge the device slightly faster.
When charging, observe the following: The optimum charging voltage of chargers for lithium-ion batteries is 4.2 volts. Most chargers with their charging voltage of about 5 volts are still within the tolerance range. In addition, they generally transmit a current between 700 and 1000 mA to the batteries. Ensure that the charging current of the chargers in mA is approximately 0.6 to 1 times the battery capacity in mAh of the smartphone battery. Higher current ratings can reduce battery life, while lower power ratings may overheat the charger.