Information

The host initiates transactions to specific peripherals, whereas the device responds to

control transactions. The device sends and receives data to and from the host using a

standard USB data format. USB 2.0 full-speed /low-speed peripherals operate at 12Mbit/s

or 1.5 Mbit/s.

For additional information, see the USB 2.0 specification.

External Hub

Root

Hub

USB Cable

External Hub

USB Peripherals

Host PC

Host

Software

USB Cables

Figure 40-1. Example USB 2.0 system configuration

40.1.2 USB On-The-Go

USB is a popular standard for connecting peripherals and portable consumer electronic

devices such as digital cameras and hand-held computers to host PCs. The On-The-Go

(OTG) Supplement to the USB Specification extends USB to peer-to-peer application.

Using USB OTG technology consumer electronics, peripherals, and portable devices can

connect to each other to exchange data. For example, a digital camera can connect

directly to a printer, or a keyboard can connect to a Personal Digital Assistant to

exchange data.

With the USB On-The-Go product, you can develop a fully USB-compliant peripheral

device that can also assume the role of a USB host. Software determines the role of the

device based on hardware signals, and then initializes the device in the appropriate mode

of operation (host or peripheral) based on how it is connected. After connecting the

devices can negotiate using the OTG protocols to assume the role of host or peripheral

based on the task to be accomplished.

For additional information, see the On-The-Go Supplement to the USB 2.0 Specification.

Introduction

K20 Sub-Family Reference Manual, Rev. 2, Feb 2012

884 Freescale Semiconductor, Inc.