USB-based systems are all around us, both in embedded systems
where USB is used as an interconnect technology between
components inside a product, and as a popular external interconnect
bus between computer and peripheral devices. An extra benefit of
the USB interface is that it supports delivery of power from the host
to peripheral devices.
The Universal Serial Bus (USB) has become a dominant interface on
today’s personal computers, replacing many of the external serial and
parallel buses previously used. Since its introduction in 1995, USB has
grown beyond its original personal computer usage and has become a
ubiquitous interface used in many types of electronic devices.
USB has expanded beyond just system-to-system communication.
For example, the Inter-Chip USB (IC_USB) and the High-Speed Inter-
Chip (HSIC) USB are used for chip-to-chip communications.
USB 2.0 is a mature standard and many of the building blocks are
robust. However, these buses can be impacted by noise, board
layout, termination and other factors. In case of bus communication
failures, an oscilloscope is the go-to tool for providing timing and
amplitude information initially, and when equipped with decoding
capability, also protocol-level diagnostic information.
Even when the USB bus is operating correctly, other systems can
suffer problems under specific conditions. In these cases triggering
on specific USB bus values can provide a critical time reference to
help troubleshoot system-level bugs.