The original USB bus came in like a storm. In just a couple years it nearly replaced all other common PC connectors. First was the USB A and USB B plugs and sockets and the 1.0 specification. They provided low speed (1.5 Mbps) and full-speed (12 Mbps) data transfer rates and a method for identifying what type of device was being connected to the bus. In addition the USB Specification also provided for HUB devices that allow the bus to be used by multiple devices. Though only one may transmit at a time.
Next came USB 2.0 and USB-OTG (On The Go). These added even faster transfer rates (480 Mbps) dub SuperSpeed and the ability to be a bus master or client respectively. The OTG specification was truly helpful to devices like mobile phones where at times you want the device to act as a host and at other times act like a client.
USB 3.0 up’d the data transfer speed to a maximum of 4.8 Gbps and increased the available power on the bus from 100 ma to 900 ma. This allows for either more bus powered devices on the bus or a single high powered device on the bus such as portable disk drives. The speed increase allows large files to be transferred much more quickly. While USB 3.0 increased available power, the interface is actually more energy efficient than USB 2.0. With asynchronous polling, USB 3.0 has the peripheral alert the host only when data needs to be transferred, therefore reducing power demands. With USB 2.0, energy was wasted with continuous polling. SuperSpeed also has the computer or devices reduce power when idle through link level power management. The LPM feature first appeared in some but not all USB 2.0 devices because it was difficult to integrate. However, it is a standard feature in USB 3.0. The 3.0 standard also required USB ports and plugs to be colored bright blue. This allowed anyone with sight to easily recognize a 3.0 device or port even though the cabling is mostly backwardly compatible with 1.0 and 2.0 devices.
USB Type-C is not exactly new. It’s been in the works since 2012 however, some parts of the specification were not ratified until January, 2017. Still, you may have already seen USB Type-C in use on the newest cell phones, laptops or mobile devices. So what makes this new USB specification noteworthy? Well, to start with, it’s built for convenience. The connector is similar in size to a USB Micro Connector. It sports smooth rounded ends that allow the connector to be plugged into a USB Type-C socket in either direction while maintaining correct signal wiring. The USB 3.1 Standard used with a Type-C connector allows for programmable bus voltages from 0 to at least 20 VDC with currents of up to at least 3.0 Amps. The bus however always starts in what the specification refers to as Safe5v, a 5 VDC voltage. Higher bus voltages are then negotiated on the bus and may be increased up to 20VDC at 4Amps. That’s a 100 watts of power, more power than the average laptop power supply! In addition, the 3.1 specification also increases the maximum data transfer rate to 10Gbps.
One issue that may cause some confusion is that the Type-C plug and socket can be used with previous USB versions. This allows manufacturers to stay with less costly hardware until they feel the need to upgrade. Also, the 3.1 specification has no required color coding that I could find. This will confuse people expecting high power device to work with a Type-C cable when the Type-C connector is used with 2.0 or 3.0 host hardware. Some of these devices may simply not work or experience reduced performance. Still some host device manufacturers have jumped on the 3.1 & Type-C band wagon. Apple for one embraced the new technology on many new devices even before the complete specification had been completed.
Furthermore, the Type-C connectors and sockets are not compatible with other the standard 1.0, 2.0, or 3.0 Type-A connectors found on most host devices such as laptops and PCs. So to use your printer or most other devices with a host that has a Type-C connector (even if it is sporting only USB 2.0 host hardware, will require a Type-C to Type-A adapter.
You can find more information on the various USB Standards at: www.usb.org the developer’s page at: www.usb.org/developers was most helpful and contains links to tools for debugging USB communications as well as documentation.