Specifications

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Some USB Terms
Host — computer that controls the interface
Function — device that provides a capability to the host
Hub — device with one or more connections to USB devices plus hardware to enable
communications with each device
Device — something that attaches to a USB port (sometimes synonymous with a function)
Port — a connector on the USB Host bus
Suspend — Device enters Suspend after 3mS of inactivity on the bus to minimize power
consumption. Host uses timing packet to keep Peripherals active.
Enumeration — Initialization sequence to inform the host what device was attached to the
bus. Device parameters are conveyed at this point.
Descriptors — List of tables that identify the capabilities of the device
Endpoint — All transmissions travel to/from and endpoint which is just a block of memory or a
register. Endpoint 0 is the control endpoint which is the only bi-directional endpoint typically
used for enumeration.
Descriptors — List of tables that identify the capabilities of the device
USB Ports
Here are some common terms when discussing USB. Take a moment to familiarize
yourself with these terms.