8 CHAPTER 1 Introduction
RM08001 Reference manual for J-Link USB Protocol © 2008 SEGGER Microcontroller GmbH & Co. KG
1.1 How to use this manual
This manual describes the J-Link USB Protocol used in J-Link products and how it is
used.
In the course of this document the J-Link ARM is refered to as emulator.
1.2 Purpose of this document
The purpose of this document is to allow developers of open source software such as
OpenOCD to write software which uses J-Link as debug interface.
This document gives an overview about the J-Link USB communication and how it
can be used in your application. Sample communications to almost each command
description should give you an idea of the data transferred via USB between J-Link
and host.
1.3 Features of J-Link ARM
J-Link provides a feature rich list of functions to simplify the
debugging process. All important functions which are used by
the SEGGER software are useable via the USB protocol.
J-Link ARM has many features:
•USB 2.0 interface
•Any ARM7/ARM9 core supported, including thumb mode
•Automatic core recognition
•Maximum JTAG speed 12 MHz
•Download speed up to 720 Kbytes/second *
•DCC speed up to 800 Kbytes/second *
•No power supply required, powered through USB
•Auto speed recognition
•Support for adaptive clocking
•All JTAG signals can be monitored, target voltage can be mea-
sured
•Support for multiple devices
•Fully plug and play compatible
•A Standard 20-pin JTAG connector
•Optional 14-pin JTAG adapter available
•Wide target voltage range: 1.2V - 3.3V
•Optional adapter for 5V targets available
* = Measured with J-Link Rev.5, ARM7 @ 50 MHz, 12MHz JTAG speed.
