ARM JTAG Widget

Last updated: 12 February 2007

1 off Price: GBP 145.00 with software and manuals on CD

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ARM9 support

Thumb code support

JTAG daisy chain support

JTAG Widget Software
JTAG Widget Hardware

What does it do?

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The ARM JTAG Widget provides hardware and scripting software for debugging application software and hardware on ARM7 and ARM9 CPUs. It is ideal for hardware debug and bring-up, low-level software debug and production programming of your boards. After many years of frustration with existing tools for ARM hardware and firmware development, this is the tool we need. We use it every day ourselves.

The hardware has a USB connection to the host computer, and a JTAG interface using the standard ARM 20 pin format to connect to the target device at data rates up to 8M bps. The hardware is based on our USB ARM Stamp. No more nasty parallel port issues.

The JTAG Widget has a 60MHz ARM CPU which you can control interactively through the USB connection. On the host computer it is presented as another serial port so that you can talk to the JTAG widget using a terminal emulator.

Additional I/O lines and a serial port can be connected to the target device and manipulated by the JTAG widget, so allowing the JTAG widget to be used as a test stimulus generator. This is extremely useful when narrowing down on faults that occur only very occasionally in the field. If you write test scripts as tasks, they do not interfere with the debugging facilities.

The JTAG software provides low and high level functions for JTAG access to ARM and other CPUs. The software is based around the Forth programming language. You can write your own scripts and programs which can be downloaded, compiled and saved onto the JTAG Widget ready for your next session. At the lowest level, talking directly to the JTAG widget through a terminal emulator is using a very powerful command-line debugger and Flash programmer with scripting facilities.
Download the JTAG Widget manual.
Download the Forth kernel manual.

Because the JTAG Widget uses simple communications systems, it is very easy to write programs, DLLs and shared libraries on the host computer that interface the JTAG Widget to third party compilers, IDEs and high level debuggers.

JTAG Widget Software

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The current software release is version 3.0 and supports ARM7 and ARM9 cores in both ARM and Thumb modes. XScale support is in preparation. All purchases are provided with free software upgrades for one year and full technical support.

The JTAG Widget on-board software provides all the routines required for JTAG access to ARM CPUs. Because the software is based around a Forth interpreter and compiler, you can write your own debugging scripts using the in-built commands.

• Target memory access - read/write/dump
• Target debugging - stop, start, single step, register dump/modify, breakpoints in Flash or RAM and at interrupt/exception entry, Embedded ICE access
• ARM and Thumb assemblers
• ARM and Thumb disassemblers
• File transfer configurable by the user
• CPU initialisation and configuration
• Flash programming
• RAM loader
• Use the ARM DCC as your application's console - no pins needed for a comms channel

The JTAG Widget is fast. An experiment using another device to program the Flash gave the following results:

All our Flash and CPU drivers are supplied as source code. Using the supplied AIDE software or a terminal emulator such as HyperTerm, you can download these drivers and compile them on the JTAG Widget itself. You can write new Flash and CPU drivers yourself.

When you have programmed the Flash on your target board, you can use the JTAG Widget's debugging facilities to test your application. As with the Flash and CPU drivers, you can keep the code in a text file on your PC and compile it on the JTAG Widget. There is a spare serial port and several I/O pins on the JTAG Widget are available on the JTAG IN and other connectors. These can be used with your test code to provide signals to and from the board under test.

Download the JTAG Widget manual.
Download the Forth kernel manual.

Operating systems

All the executable software supplied on the CD is for Windows. However, the JTAG Widget can be used with any operating system that supports the FTDI series of USB chips. The JTAG Widget's USB interface is through an FTDI device and a driver that simulates a serial device. Any operating system that can provide these facilities can be used with the JTAG Widget. The latest drivers for several operating systems, including Linux, MacOS8/9/X and WinCE.NET, are available free of charge from FTDI.

The software you will need is a terminal emulator with XModem file transfer utilities.

CD Software and contents

Flash and CPU driver examples. These are example configurations for ARM CPUs and Flash devices.

AIDE is an Integrated Development Environment (IDE) that includes a simple editor for your source code and a terminal emulator (PowerTerm) tuned for use with the JTAG Widget software on the board. Additional development tools can be added to the toolbar and the help menu.

File conversion tools are provided for converting between several common compiler output formats.

Full documentation is provided for the JTAG Widget hardware and software, including Forth tutorials and ARM reference manuals.

USB driver. The latest versions of these drivers are available for free download from FTDI.

Program loader. If you finally manage to upset the JTAG Widget itself, you can reinstall its own software.

JTAG Widget Hardware

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The JTAG Widget consists of several main blocks:

See the USB ARM Stamp page for more details of the hardware.