I/O Interfaces & Buses
Which statement about how USB communication works is correct (for conventional USB, excluding USB4)?
- AThe host schedules communication and queries devices, which send data as the host directs
- BAll devices are peers and can send data whenever they like
- CDevices normally communicate directly without the host
Show answer and explanation
Answer: A. The host schedules communication and queries devices, which send data as the host directs
In USB, the host, such as a PC, manages connected devices and decides which device to talk to and when. Even a mouse returns its input only when the host polls it periodically. This keeps devices simple, so many can be made cheaply. When plugged in, a device tells the host what kind it is, and the host loads a matching driver.
- A. Correct. It is host-driven.
- B. Devices cannot send on their own initiative.
- C. Communication is basically between host and device.