Free JTAG tools provide new approach to board debugging - Embedded.com

Free JTAG tools provide new approach to board debugging

LONDON — JTAG Technologies (Eindhoven, The Netherlands) is introducing a new approach to supplying tools for debugging boards with a mix of free and paid for products targeted at different aspects of the debugging process.

JTAG Live is for electronics engineers and technicians to use in checking PCBs for basic continuity and correct operation. The family consists of three products, Buzz, Clip, and Script.

And to keep start-up costs down, to connect to the board, JTAG Live is compatible with the popular JTAG programming cables from Altera and Xilinx, as well as with the two-port USB Explorer from JTAG Technologies.

Buzz provides the ability to check quickly (direct and indirect) connections between devices supporting boundary-scan while Clip offers ways to verify cluster logic using vector-based cluster tests; and Script enables users to adopt a functional, device-oriented test approach to take control of a design through on-board JTAG/boundary-scan compliant devices.

Buzz is available free of charge from the JTAG Live website. Clip and Script are also available for download, but for a nominal charge.

JTAG Live is designed to make use of the boundary-scan circuitry found on high-end boards. There is no need for a netlist as the tools use boundary-scan description language (BSDL) files, available from the IC vendors, to identify device inputs and outputs for driving and sensing. Users are able to define up to two boundary-scan chains and verify chain integrity.

The 'watch' window in Buzz shows the current logic state (high, low or toggling) of any selected boundary-scan pin. Buzz also gives hardware design engineers a practical way to check continuity between two pins on a prototype board; mimicking the familiar buzz measurement done with digital multimeters (DMMS) but without probes.

Within the 'measure' window of Buzz, a user selects a pin to be driven, sets it high or low, and reads the resulting value on the sense pin. Going beyond the functionality of a DMM, Buzz also shows multi-pin nets. Users can easily drive one pin to many to check for correct fan-out connectivity or from multiple pins to one or more sense pins to perform a test on bus lines or to verify a simple cluster comprising of one or more logic gates.

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A portion of the JTAG Live test module.

Clip allows engineers to debug more complex clusters using vector-based cluster test sequences. Each vector in a sequence contains a set of input values for device or cluster inputs and a set of expected cluster output values. The Clip user interface offers a logic analyzer / pattern generator-style state and timing display mode for defining vectors and observing test results. Tests created within Clip can be saved and recalled for testing multiple boards of the same type.

The third member of the JTAG Live family, Script, provides a powerful API to manipulate and sense cluster I/Os. Script is ideal for users wanting a functional, device-oriented test approach for mixed-signal device testing, operations that require user intervention, and test pattern looping for setting up device registers.

Within Script, users employ the open-source programming language Python to check interconnects and verify the operation of non-boundary-scan clusters. Through high-level routines embedded in a Python program, Script drives and senses values on pins or groups of pins. The built-in Python editor facilitates preparation of the sequences to perform tests and collect results.

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The Python module can be used to set, drive and sense values JTAG-compliant pins or groups of pins. The Python language then handles the low level shifts, loops, branches and compares, enabling the verification of the operation of non-boundary-scan clusters. Sample Script programs are included for RAM testing, flash ID reading and flash in-system programming.

In addition to the software download section, the JTAG Live website includes product descriptions, answers to frequently asked questions, and highlighted experiences from JTAG Live users.

With an installed base of more than 6,000 systems worldwide, JTAG Technologies serves the communications, medical electronics, avionics, defence, automotive, and consumer industries with its boundary-scan products providing test preparation, test execution, test result analysis and in-system programming applications.

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