Information

The host initiates transactions to specific peripherals, while 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 12Mb/s or 1.5

Mb/s.

For additional information, refer to the USB 2.0 specification.

External Hub

Root

Hub

USB Cable

External Hub

USB Peripherals

Host PC

Host

Software

USB Cables

Figure 42-1. Example USB 2.0 System Configuration

42.1.2 USB On-The-Go

USB (Universal Serial Bus) 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 (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, refer to the On-The-Go Supplement to the USB 2.0

Specification.

Introduction

K20 Sub-Family Reference Manual, Rev. 6, Nov 2011

1048 Freescale Semiconductor, Inc.