Summary of GNU/Linux & USB - Universal Serial Bus (USB) Theory

00:00:00 - 00:15:00

This video provides an overview of USB theory and how it works, with two examples of how USB can be used. It also explains how to program a USB device and use a flashing tool for Linux to support it.

• 00:00:00 The physical interface of USB allows for two connectors- a USB type A on the left, and a USB type B on the right. USB 2.0 features four pins, with pin one being 5 volts, pin two being differential data, pin three being 3.3 volts, and pin four being ground. USB speeds include high speed (480 megabits per second), full speed (12 megabits per second), and low speed (1.5 megabits per second). When a USB host detects a connected device, it pulls the data lines to ground to power the device and send data. USB also has a tiered starter policy with the host in the middle, and allows for up to 127 devices to be connected to a bus.
• 00:05:00 The USB transfer types are Control, Over Control, Interrupt, and Bulk. Control transfers are used for controlling and enumerating the device, assigning a bus address, and transferring data. Over Control and Interrupt transfers are guaranteed to have a latency, while Bulk transfers are used for transferring large bursts of data. The only exception is for m.0, which is a point-zero only device that supports in and out transfers.
• 00:10:00 This video explains how USB works, and provides two examples of how it can be used. USB allows for files to be stored on a USB stick, and enables a PC to send a setup package to a USB device to initiate a transfer. The USB device can then receive and acknowledge the data packages, and write the data to a Flash storage device.
• 00:15:00 The video describes how to program a first USB device, and then how to install and use a flashing tool for Linux to support it.