A USB connection depends on a complete physical and logical path. Hubs, cables, power sources, host capabilities, and accessory requirements can each influence the functions available through that path.
The bigger picture
A hub expands a topology rather than creating unlimited independent bandwidth. A cable can differ in supported signaling and power handling even when its connectors resemble another cable's. Power negotiation and data negotiation also describe separate relationships, so charging behavior should not be used as the only test of data capability.
The operating system observes connection and removal events through the host controllers and hubs. It then coordinates discovery and the software associated with exposed functions. A hub adds another level to this topology. The topics below explain these roles without instructing readers to alter electrical settings or firmware. Use manufacturer documentation for the limits of an actual combination, especially where charging or display functions share a connector.
USB & Peripherals
Note these before you change anything
Useful facts to have to hand while reading about usb cables, hubs and power.
- Which port the device was in, and whether a hub is involved
- The device's name and status in Device Manager
- Power management settings on USB root hubs
- Any companion software the device relies on
USB & Peripherals: Input from a device (output devices run the other way)
- Devicekeyboard, mouse or pad
- Port or hubphysical connection
- Host controllermanages the bus
- Class driverfor example HID
- Applicationreceives the input
Pages in USB cables, hubs and power
USB hub topology and shared paths
A USB hub adds downstream connection points beneath an upstream path. It helps the host discover and communicate with attached equipment, but it does not…
USB cable capabilities and labels
A USB cable's connectors describe how it physically fits, but its construction determines which signaling and power arrangements it supports…
USB power negotiation
USB power negotiation lets supported equipment agree on an electrical supply arrangement within their documented capabilities. It is separate from the…
USB connection and removal events
Connecting or removing a USB accessory changes the topology the host observes. The operating system responds by discovering functions, starting or stopping…
