JTAG is an acronym for ‘Joint Test Action Group’, an organisation that started back in the mid 1980’s to address test point access issues on PCB with surface mount devices. The organisation devised a method of access to device pins via a serial port that became known as the TAP (Test Access Port). In 1990 the method became a recognised international standard (IEEE Std 1149.1). Many thousands of devices now include this standardised port as a feature to allow test and design engineers to access pins. JTAG Live is the first software to offer this access in a quick easy and free environment. A useful reference site is www.boundary-scan.co.uk

There is no difference. In fact the IEEE Std 1149.1 has a full title of ‘Boundary-scan and Test Access Port architecture’. However some device vendors claim to have a JTAG port but are not compliant to IEEE Std. 1149.1. In these instances check thoroughly the extent of the implementation and the availability of the BSDL model (see FAQ: What are BSDL files and where do I get them?).

JTAG Live  is a fantastic new hardware design debug tool set from the world’s most experienced JTAG development house. JTAG Live includes a fully functioning freeware module, JTAG Live Buzz, plus upgrade options for more applications.

A JTAG Live license, whether purchased or free, is valid for 12 months. After 12 months, simply renew your license free of charge at the My JTAG Live section of this web-site. You can ofcourse do this as many times as you want, the software, purchased or free, remains yours unlimitedly.

No. The user just needs to define the JTAG / boundary-scan chain by a ‘drag & drop’ of BSDL files into the scan chain window.

BSDL files or models describe the JTAG or boundary-scan operation of a device in full detail and are primary ingredients in JTAG software products like JTAG Live. They use a subset of VHDL to describe the logical content of the device that is described fully in IEEE Std.1149.1b.

Any manufacturer that states their device is compliant to IEEE Std 1149.1 is obliged to make this file available to it’s customers. You will typically be able to download BSDLs from the manufacturer’s web-site or by request at a support mailbox.

There is no limit on the number of devices that a design can support.

This will more likely depend on your chosen controller. JTAG Technologies controllers can handle two or four scan chains, Altera ByteBlaster is only one. However due to the easy drag and drop method of defining chains, multiple chains can be merged by daisy chaining external to the board if needed.

BSDL files or models describe the JTAG or boundary-scan operation of a device in full detail and are primary ingredients in JTAG software products like JTAG Live. They use a subset of VHDL to describe the logical content of the device that is described fully in IEEE Std.1149.1b.

Any manufacturer that states their device is compliant to IEEE Std 1149.1 is obliged to make this file available to it’s customers. You will typically be able to download BSDLs from the manufacturer’s web-site or by request at a support mailbox.

JTAG Live features extensive syntax and semantics checking any devices failing to import will be accompanied by an error report which can be used to help fix the error. If this is not possible then report the failure to the device vendor and not JTAG Live. JTAG Live has no control over the content of these models. BSDL files that state compliance to JTAG Technologies syntax check should import without hindrance.

Each window can support ten drivers and ten sensors that can be merged where needed (so ten two node nets or one twenty node net). What’s more up to ten sessions can be opened giving the user a total of 100 drivers and sensors that can be set-up in a single project.

Yes. Clip allows users to specify groups of boundary-scan compliant pins and subsequently set them as read (input) or write (output) per vector or pattern – vector sets are unlimited in length but can only be run in a linear or sequential manner. Single stepping and breakpoint setting is included however. For test pattern analysis, looping and conditional branching choose JTAG Live Script.

The JTAG TRST (Test Reset) signal is optional according to IEEE Std 1149.1. If your design has no TRST do not worry, it maybe that none of the devices you have used feature this signal in their JTAG pin-out. If your design does feature TRST on some or all devices then you must connect to the TRST pin of your JTAG controller to ensure it is pulled high during testing. If your controller does not feature TRST then you must endeavour to tie it high via a pull-up resistor for the duration of the testing session.

To enable a quick start-up and overall ease of use, the JTAG Live product family does not support the import of netlists. However JTAG Technologies, the company that developed JTAG Live, also created JTAG ProVision – a fully-enabled developer suite that automates interconnect test generation, memory testing, flash programming and much more besides. Please visit www.jtag.com for more details and an on-line video demonstration of ProVision.

JTAG Live features extensive syntax and semantics checking any devices failing to import will be accompanied by an error report which can be used to help fix the error. If this is not possible then report the failure to the device vendor and not JTAG Live. JTAG Live has no control over the content of these models. BSDL files that state compliance to JTAG Technologies syntax check should import without hindrance.

Xilinx III, IV (parallel)pods plus Xilinx USB cables have been tested with JTAG Live.

However it is important that the following guidelines are met before use:

1) ISE WebPack (including iMPACT) V11.1 or later is installed.
2) Your environment variables are set correctly as follows:

XILINX=C:XilinxISE11.1
PATH = $XILINX$libnt;$XILINX$binnt;%PATH%

Note that this is the minimum requirement for the cables to work. Note also that if older versions of ISE appear before these, then this can cause the cable to stop working in Buzz.

The Altera USB Blaster has been tested with JTAG Live. However it is a pre-requisite that Quartus II Programmer 9.1 or later is installed. This is a free download  (this programmer is also available as part of the full Quartus II suite).

Make sure your firewall is not blocking the auto-updater (updater.exe)

Python is a general-purpose high-level programming language that supports object-orientated programming. It was initially developed in the early 1990s by Guido van Rossum and is now controlled by the not-for-profit Python Software Foundation, sponsored by (among others) Microsoft and Google. The Python implementation is under an open source license that makes it freely usable and distributable, even for commercial use.

To program flashes and SPROMs (I²C or SPI for example) is easy with the JTAG Live Script upgrade. With Script, Python routines you will find sample Python modules for testing and programming devices such as NOR flash.

Yes and no. JTAG Live Buzz does not support loops, however by upgrading to JTAG Live Clip or JTAG Live Script you can get this feature. In Clip the system is interactive and requires no coding. In Script we harness the power of the Python language which offers many types of ‘flow control’.

The Watch feature is essentially an activity indicator that uses the JTAG sample mode to monitor an individual pin in real time. It does not affect the normal operation of the device BUT the sample rate cannot be guaranteed to capture all events.

Yes. Clip allows users to set walk-1, walk-0 or binary count patterns across a given group of boundary-scan pins.

Yes. Compliance bits are detected by the BSDL model parser and warnings issued to the JTAG Live user.

For simple address and acknowledge tests JTAG Live Clip is sufficient.

For testing of devices that can be programmed with variable data and/or can offer variable results that must be checked against limits (e.g. ADCs) then the programming features that JTAG Live Script offers are most suitable.

Yes in order to test for a clock presence (but not frequency – the sample rate is likely to be far too low) then you can use the features within JTAG Live Script to repetitively sample an input for toggling.