Building upon the board-level and system-level guidelines presented in the Design for Test eBook series, in this fourth eBook, we examine a software application developed by ASSET InterTech named ScanWorks Dispatcher.
System-level JTAG, or SJTAG, expands the application potential of JTAG significantly beyond the traditional board-level scope of structural tests. System-level JTAG is well-suited for functional tests, device programming, and in-situ diagnostics.
This eBook will chronicle our own experiences with dealing with these problems and use a Commercial Off the Shelf (COTS) board to delve deeply into the testing. We will emphasize the testing of DDR memory both structurally and functionally.  A Design For Test (DFT) analysis of the target board starting with the System on Module (SOM) and continuing with the Carrier Card (CC) will be described.
Download this e-book and learn all there is to know of about the boundary scan JTAG (TAP) architecture and the problems it solves to create high test coverage.  Written by Dr. Ben Bennetts, a leading Design For Testability (DFT) expert who has worked for GenRad, Synopsys and LogicVision. Additional content has been added to this e-book by ASSET’s own Chief Technology Officer Adam Ley and Application Engineer Ben Bales.
As this eBook enters its 3rd edition, content has been added describing some of the latest advancements in DDR memory, power, speed, and test technology. New memory devices such as DDR5 which utilize CT mode, and Graphics Double Data Rate 5 (GDDR5) SDRAM and GDDR6 Synchronous Graphics Random Access Memory (SGRAM) devices that implement forms of boundary-scan test technology, are described herein.

ScanWorks users can bridge the coverage gap between boundary scan and functional test via its Component action. This action allows for testing of non-boundary scan devices, such as analog to digital converters (ADCs), digital to analog converters (DACs), Ethernet PHYs, LED, switches, clocks, and other non-boundary scan devices through the PCBs boundary scan infrastructure.