What is XJTAG?

Overview

XJTAG provides a set of tools which specialise in using IEEE 1149.x JTAG Boundary Scan to test and/or program populated Printed Circuit Boards (PCBs).

JTAG is designed for testing populated PCBs without requiring the level of physical access needed for traditional bed-of-nails testing, or the amount of development work required for functional test. The JTAG boundary scan standards are supported by most CPUs, FPGAs and CPLDs, and XJTAG is able to extend test coverage to peripherals and other non-JTAG devices in the circuit, using access given by the JTAG-compliant devices.

XJTAG is designed to be used both in a design/prototype environment and in a factory situation. The physical access requirements to the PCB are minimal, and so boards can usually be meaningfully tested even where a test jig/fixture is not available. XJTAG products are designed so that the same tests can be re-used when a product moves from the prototype stage into mass production.

Products and Features

The XJTAG product range consists of a suite of software products and a set of JTAG controllers such as the XJLink2 and XJLink-PF40, which enable users to test and program electronic circuits. It has been designed to unlock the potential of JTAG.

For projects where a netlist is provided, XJTAG includes a number of features to assist in finding and diagnosing faults quickly, including built-in Schematic and Layout viewers. These features are available in XJDeveloper, an IDE tool for test development, and in XJRunner, a tester aimed at production environments.

XJTAG projects can use an automatically generated interconnection test, which adapts to circuit responses to diagnose any problems, whilst the in-built XJEase language is easy to learn and allows custom tests to be written, though it also supports thousands of devices using the provided XJEase library. XJEase is designed so that when a test is written for a device, the same file can be re-used wherever the device is encountered, whether this is another instance in the same circuit, or in an entirely different project.

If a netlist is not provided, or for low-level debugging operations, XJTAG's XJAnalyser software allows significant control of the product using a straightforward graphical interface in which you can click on a pin to set its value.

Integration

XJTAG is able to integrate and interoperate with a variety of other test equipment at a software or hardware level. Software such as LabVIEW can control XJTAG, or XJTAG can make calls to make measurements using other programs.

XJTAG offers versions of the XJLink2 JTAG controller for use in various types of ICT machine, and corresponding software integrations with those systems.

Command-line XJTAG utilities allow tools with lower levels of integration capability the ability to run XJTAG tests, with output in plain text.

Key benefits of XJTAG

Entire Product Lifecycle

Any tests developed for a device or board can be reused at any point in a product's lifecycle - development, prototyping, testing, production and maintenance.

Device-centric re-usable tests

Any functions developed to test or program a particular device are independent of the circuit in which the device is used, and can be re-used in new circuits as needed.

Non-JTAG Component Testing

Writing a test for a non-JTAG device is easy, as long as the relevant pins are on nets controlled by the JTAG chain.

BASIC Style Language

The XJEase language is quick and easy to learn and use. New tests can be written and old ones adapted in a matter of minutes.

Device Model Library

XJTAG includes a large library of XJEase device models, speeding up the setup process considerably. Source code is freely editable meaning these files can be used as they are, or adapted to meet new requirements.

Reactive Test Pattern Generation

Test patterns are created "on the fly", so the results of previous test patterns are available. This means that tests can adjust their behaviour depending on what is found, to better identify the nature and location of faults.

Abstraction from Details of JTAG

The user simply has to describe what happens to the pins in the circuit; the XJTAG software operates the JTAG interface automatically as needed, meaning the user does not need to understand how the JTAG protocol works.