XJTAG has included partial support for the standardised PCOLA/SOQ method of measuring test coverage for some time. The recent XJEase library update, library version 181, contains PCOLA/SOQ data for the test coverage of devices, completing this functionality.

Prior to this library version, XJTAG has been able to calculate some PCOLA/SOQ data based on coverage from interconnect testing, but device models have not contained PCOLA/SOQ data for the coverage obtained through the XJEase tests. This is now present throughout the XJEase library and means that the generated PCOLA/SOQ data is much more complete.

XJEase Library version 181 needs XJTAG version 3.10.6 or later for full compatibility.

The initial step of creating groups of devices, and assigning appropriate weights to the PCOLA/SOQ properties is automatic. It is predominantly derived from the device categorisations in XJDeveloper, with extra information from assigned library files. Below is a brief overview of the scores that XJTAG can give – more detail is included in the help files.

For JTAG devices, because XJDeveloper can read the ID Code of a JTAG device in the unit under test, it is often possible to award full Presence and Correctness cover. Because it’s highly unlikely that anything could be returned at all if the device were not correctly oriented, full Orientation cover can also be awarded. Scoring the Live property is a little more complex – it is possible, particularly on a device with multiple power pins – that only the boundary scan cells are operating. So only a partial test coverage score for Live can be given.

Scores for Test devices can be added to the device files (and this is done if the file comes from the new XJEase library version 181 or later) – since those files already describe the test . For a device using non-library file the scores can be added using the PCOLA Scores tab in the Test Device File editor. (This can also be used to remove scores from the device files if it becomes necessary to use them in XJTAG 3.8 or prior.)

Logic devices are awarded test coverage and PCOLA/SOQ scores by XJTAG if they are tested by the Connection Test, or are involved in driving or reading from a Test device.

Passive devices will only contribute to the PCOLA/SOQ scores if they are using files from the XJTAG library. The type of the passive device, and its position within the circuit can result in various different scores for these components. For example, resistors always receive a Not Applicable score for their Orientation property because there is no “right” way round, and the weight of the Orientation score will be set to zero.

Of course, if there are devices that XJDeveloper can’t score – uncategorised or ignored devices, or passive devices using custom files – and the user knows of tests that cover those devices, scores can be manually entered to incorporate those tests into the statistics displayed in Developer. You can do this from the PCOLA/SOQ tab of the Test Coverage screen, selecting the board and adding a device group.

One of the aims of PCOLA/SOQ is to allow combination of test coverage from different test sources, so you can export the PCOLA/SOQ data from the Test Coverage screen in XJDeveloper if you wish to import it into another tool of your choosing.