Free-for-Life Tool Cracks PCB Debug Challenge

The JTAG Live family consists of three products, Buzz, Clip, and Script - each of which is targeted at different aspects of the debugging process.

• Buzz provides the ability to check quickly (direct and indirect) connections between devices supporting boundary-scan;

• 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.



To support easy access and quick start-up, Buzz is available free of charge from the JTAG LiveTM website, www.jtaglive.com. Clip and Script are also available for download, but for a nominal charge.



JTAG LiveTM capitalises on the boundary-scan circuitry found on today’s 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 easily up to two boundary-scan chains and quickly 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 DMM buzz measurement 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.



Clip, the second member of the JTAG LiveTM family, 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 LiveTM 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 PythonTM to check interconnects and verify the operation of non-boundary-scan clusters. Through high-level routines embedded in a PythonTM program, Script drives and senses values on pins or groups of pins. The built-in PythonTM editor facilitates preparation of the sequences to perform tests and collect results.



To connect to the board, JTAG LiveTM is fully compatible with the popular JTAG programming cables from Altera and Xilinx, as well as with the two-port USB Explorer from JTAG Technologies.



The JTAG Live TM software family is available immediately for download from www.jtaglive.com. In addition to the software download section, the site includes product descriptions, answers to frequently asked questions, and highlighted experiences from JTAG LiveTM users.