XJLink2 — USB JTAG controller

XJLink2 is a small, portable, USB hardware device that provides a high speed interface to the JTAG chain on a circuit board.

The small, lightweight design means the XJLink2 can easily be moved to the Unit Under Test (UUT). Advanced features, like their programmable JTAG signal pin position, switchable power supply and auto signal skew, make it easy to connect to a wide range of circuit boards. Simple to install and use due to the USB plug-and-play ability.

Key Benefits

  • Small, lightweight, portable design: ideal for lab and field work
  • Self-contained licence so you can use the XJTAG system on multiple PCs
  • Re-configurable unit for multiple UUTs saving costs

XJLink2 datasheet XJLink2 technical specifications Get further info

XJLink2 - second generation USB-to-JTAG hardware interface


  • Connects to up to 4 JTAG chains on the UUT
  • Configurable JTAG connector pinout to suit any cable or board
  • USB bus-powered (no external PSU)
  • TCK clock frequencies up to 166 MHz
  • Two different voltages can be configured, from 1.1 V to 3.3 V in 0.1 V steps
  • Button to start test
  • Visual indication of test status
  • High speed USB 2.0 interface, backwards compatible with USB 1.0 & 1.1
  • Adjustable JTAG signal termination
  • Spare pins on the JTAG connector can be used in place of the button or to indicate the test status
  • Pins can also be used as general purpose I/O during testing, for example for fast Flash programming
  • Spare pins can be used to control other items — e.g. hold a board in reset / turn on a PSU
  • Automatic signal skew control
  • Can supply power to the target board through the JTAG connector (3.3 V, <100 mA)
  • Built in voltage meter on all I/O pins. Voltage input: Min 0, Max 5 V
  • Frequency counter on all I/O pins. Frequency input: Min 1 Hz, Max 200 MHz.
  • Selectable measurement period of 1 ms, 10 ms, 100 ms, 1 s, 10 s
  • JTAG signals are +5 V tolerant
  • Simple DLL API interface: includes commands such as tmsReset() irScan() drScan() etc.
  • Available in two colours allowing users to differentiate between units with different licences

Configurable JTAG interface

Because there is no standard JTAG header or pinout, the XJLink2’s JTAG connector is configurable in software to allow you to select the pinout that best suits the board being tested. Two of the connector’s 20 pins are fixed grounds, but the JTAG signals for up to four chains can be distributed across the other pins as needed, with any spare pins assignable as digital I/O.

Advanced connectivity

XJLink2 has variable signal termination, so it can handle boards both with and without signal termination. The advanced auto-skew control enables you to get the maximum frequency out of your JTAG chain and cable while the configurable voltage levels allow you to connect directly to most TAPs (Test Assess Ports).

Your test system where you want it

The controller contains the license for your XJTAG system. This allows you to easily move your licenses around on and off site to give you maximum flexibility. This also means you aren’t tied to one machine to do your XJTAG testing.

Light & portable

XJLink2 can work with a laptop PC with a USB port and can supply power to low-power target systems, so testing can be done even without a source of mains power. This is especially useful if testing has to be done in the field or in a very busy lab.

Simple DLL API interface

The hardware can be sold separately from the software, with a simple-to-use DLL API interface. We can craft the API to meet whatever needs you have for the system.

The API header file is available for download: XJAPI.h

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