Connect - ASSET InterTech

Reducing test points reduces costs
By Dave Bonnett
Technical Marketing Manager
ASSET InterTech

With the new version of ScanWorks (3.8) maintenance users will be able to automatically take advantage of the new Test Point Reduction Report, a utility that reorganizes a PCB’s coverage information to make it easy to determine where there is redundant test coverage provided by both boundary scan and in-circuit test (ICT). When this is the case, it makes sense to eliminate test points and rely on boundary scan for the test coverage.

Saving Fixture Costs

ScanWorks’ new Test Point Reduction Report does not eliminate test points from the design, but it gives engineers the information they need to decide with a high degree of confidence whether a test point or group of test points can be removed from the design without sacrificing test coverage. To facilitate effective design decisions, areas of redundant test coverage can be highlighted in graphical views of the design’s layout and schematic. The output of the Test Point Reduction Report is provided in an XML format so the data can be easily imported into PCB layout and fixture design tools.

Reducing the number of test points in a design has significant effects on the cost of ICT test fixtures and their maintenance, as well as a manufacturer’s overall cost-of-test. In another article in this issue of Connect (click here to read “Streamlining JTAG testability accelerates tool’s return-on- investment”), a large electronics manufacturer found that reducing test points racked up cost savings in three ways:

This OEM estimated that if it could extend JTAG test coverage and cut as many test points as possible, it could save close to $10,000 on each of its complex PCB designs.

The ASSET web site features a white paper that details a study by Lucent Technologies which found that it could save almost $700,000 a year just by reducing the number of test points on its ICT test fixtures. (For the complete white paper, click
here.)

The ScanWorks 3.8 release contains several other new features that extend users’ JTAG test capabilities, simplify the management of the boundary scan test process and automate users’ access to ASSET’s support department.

External I/O Management

A new optional addition to ScanWorks, External I/O Management, extends test coverage through resources that are external to the unit under test (UUT). Currently, two such external resources are available. They are ASSET’s ScanWorks BSIO-400 and the AccessExtender™ from JEK Technologies (www.jek-tech.com). Previously, test coverage for opens on off-board signals ended at the JTAG device closest to the connector. By adding external test resources to the off-board signals, test coverage for opens is extended through the connector, increasing the percentage of fully covered nets.

Earlier versions of ScanWorks required that the BSIO-400 netlist be merged with the UUT’s netlist to create a single design. This could have resulted in misleading test coverage data since test hardware (BSIO-400) nets and pins were included with the UUT’s test coverage calculations. With the new External I/O Management no net list merging is required and the external resources are not included in the coverage reports generated by ScanWorks for the UUT. This also eliminates the need to purchase the optional Netlist Merge feature to use the BSIO-400 or AccessExtender. External I/O Management is available at a list price of $5,895.

SigmaQuest™ Test Probes

Another new feature of standard ScanWorks is active links into SigmaQuest’s test monitoring system. With this capability, users can monitor their ScanWorks test results from anywhere in the world. SigmaQuest provides a system of test probes which monitors tests and automatically logs the results in local or remote databases. Test results can then be extracted for further manipulation or analysis.

Specifically, ScanWorks information on scan path verify actions, interconnect tests and Memory Access Verification (MAV) operations is flagged by SigmaQuest and compiled for analysis of manufacturing test processes.

ScanWorks now is able to program microprocessors, EEPROMs and other types of devices through the Serial Peripheral Interface (SPI). Since the SPI interface is present on many different devices, ScanWorks users have greater flexibility to program a greater number of devices in-system. In addition, applying the model-based programming methodology of ScanWorks simplifies the process for SPI devices.

To perform in-system programming via SPI, ScanWorks first automatically determines whether the device can be accessed by JTAG. During SPI programming, ScanWorks supports the same features and source file formats as it does for programming via the I2C interface or when programming flash memories. These formats include binary files, Intel hex files and Motorola S-Record files.

Automation Features for Support

Certain services of ASSET’s Support Department have been automated to provide more responsive and pro-active service to users on maintenance contracts. Now, when ScanWorks is launched, it will automatically check its version number against the latest release and service pack that's available. If a new version or service pack is available, ScanWorks will notify the user so he can decide whether to download the updates. In addition, ScanWorks will automatically notify users when maintenance is set to expire within 30 days, enabling them to renew their maintenance contract in time to ensure uninterrupted access to all the features of the Maintenance Benefits web site. Both of these features can be disabled at the user’s discretion.

Previously, users were required to go to the ASSET Support website to create support tickets. Now, ScanWorks saves users time and eliminates this inconvenience by launching the support wizard and completing a support ticket from within ScanWorks. The support wizard automatically loads the ScanWorks project and version information into the ticket giving ASSET application engineers a head start analyzing the issue.

New Features in ScanWorks 3.8