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External Hardware

Non-JTAG test equipment

XJTAG can operate 3rd party non-JTAG test equipment (NJTE) simultaneously with JTAG during tests. This means that test coverage can be extended by verifying that signals can be driven by JTAG and detected on the external equipment or vice versa.

This non-JTAG test equipment is referred to generically as "External Hardware", and is typically devices such as bed-of-nails testers or flying probe test machines; XJTAG will increase and broaden the range of supported devices as opportunities arise to cooperate with the manufacturers of the other devices.

Some elements of the XJTAG GUI refer to external hardware as NJTE when space is limited.

XJTAG represents the external hardware as another board in the test system, with connections to the device under test. Typically these connections are specified in the configuration for the external hardware rather than as connections in the XJTAG project.

Configuring XJTAG to use the external hardware is therefore done from the Boards Screen in XJDeveloper, selecting the board which the external hardware will be connected to, and clicking the External Hardware button.

Non-JTAG pins on an XJLink

XJLink pins that are connected to the UUT can also be used for non-JTAG testing by setting their type to PIO on the Pin Mapping screen, and adding the connection between the XJLink and the UUT on the Connections Screen.

Testing with JTAG or external hardware

In order to run tests, your project must be correctly configured to run with either JTAG, external hardware or both.

When running tests using JTAG chains:

  1. You must have at least one complete JTAG chain
  2. You can optionally have external hardware configured

To test without JTAG chains defined in the project:

  1. You must have Optimised scans enabled in your project.
  2. You also need either or both of:
    • External hardware configured in your project, or
    • PIO pins configured in the Pin Mapping screen and a connection defined from the XJLink to the UUT.

If your project does not meet either set of requirements, you will not be able to run tests and will be shown an error if you attempt to start testing. If you have any project errors, you must also resolve those before attempting to run tests.