Embedded Test Circuits Recall that boundary-scan testing embeds test circuitry in a product as part of its design. Compatible devices use dedicated shift registers and state machines to execute the boundary-scan functions. Using boundary-scan you can access assemblies or even complete systems for debugging. The data that's sent to the device can stimulate the device's core, or drive signals outward from a chip to a circuit board. You can also sense the input pins from a board, or sense device outputs, testing a device or assembly for structural faults.
Scan chains permit serial access to every pin on every device that's part of a chain.
Many designers use boundary-scan to test microprocessors, DSPs, ASICs, PLDs and the like, including support glue, interconnects, and associated connectors. Scan can interactively debug prototypes during development, and then be used in production settings to ensure quality and find faults in a manufacturing sequence. As a test step prior to a product's overall functional testing, you can use boundary-scan to find manufacturing faults that would otherwise result in a product hitting the scrap pile if it failed to function correctly. JTAG Visualizer accepts input data as schematic, layout, and information files from a variety of sources, and then provides a graphical way for you to rapidly grasp what's happening in a boundary-scan application. Using JTAG Visualizer, you can see full or partial boundary-scan areas on a board.