Pro lesson · Preview

USB Basics

Host-controlled, self-describing, and far more complex than UART: enumeration, descriptors, endpoints, and the four transfer types, plus device classes like CDC that need no custom driver.

22 min read

In this lesson:

USB's host-centric model (one master, passive devices)
enumeration: how a device introduces itself on plug-in
descriptors and endpoints, the device's self-description and data channels
the four transfer types (control, bulk, interrupt, isochronous)
device classes (CDC/HID/MSC) and why you use a USB stack, not raw registers

USB is far more complex than UART/SPI/I2C. This is the conceptual map, on an MCU you drive it through a vendor stack, not bare registers.

This lesson is part of Pro

Upgrade to unlock the full lesson and the complete interview Q&A.

Unlock with Pro

5 interview questions on this topic

Each one opens a full worked answer.

How is USB's communication model different from I2C or CAN?What is enumeration?What are the four USB transfer types and when do you use each?Why do MCUs usually implement a USB "CDC" device, and what's the benefit?A USB device fails to enumerate. Where do you look?

This is just the start

More in Communication Protocols

Serial vs Parallel, Sync vs Async UART SPI

I2C

Choosing UART, SPI, or I2C

CAN Bus

USB Basics | EmbeddedPrep.io