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Boundary Scan Description Language (BSDL): How does it make the testing process more efficient?
In the world of modern electronics, boundary scan is essential for testing interconnects (lines) on printed circuit boards. In 1985, the Joint Test Action Group (JTAG) developed a set of standards that made boundary scan technology a major advancement in the industry. As part of this technology, Boundary Scan Description Language (BSDL) has been a common standard since 1994, helping electronic device companies design effective test processes.
Boundary-scan architectures enable testing of interconnects, including logic clusters and memories, without physical test probes.
The main function of BSDL is to provide a clear description of each device that supports IEEE Std 1149.1. Such a description makes it easier for engineers to troubleshoot, test, and verify designs. In this way, when problems occur during the design process, engineers can quickly locate the problem and avoid unnecessary waste of time and resources.
Efficiency of testing mechanism
Boundary scan technology allows the test process to directly control the input and output pins of the device. This technology allows electronic devices to be tested in dense component layouts, which was very difficult in the past. Through BSDL, developers can define the behavior of each digital signal and use specific test vectors to drive the signal and check the response to confirm the correctness of the connection.
Using BSDL, designers can generate test vectors for the system, which in turn underpin the effectiveness of the boundary-scan process.
Internal Infrastructure of Boundary Scan
To provide boundary-scan capability, IC manufacturers incorporate additional logic into their devices, including scan cells that connect to external pins. These scan cells form an external Boundary Scan Shifter (BSR) combined with support for a JTAG Test Access Port (TAP) controller. This allows engineers to test integrated components as easily and efficiently as stand-alone chips on a circuit board.
Also, these designs are commonly found in Verilog or VHDL libraries, where the burden of additional logic is minimal, yet the payoff in improved test efficiency is substantial.
The Importance of Testing and Debugging
During the testing process, designers drive signals into the circuit according to different test vectors and check whether the output response is as expected. This process can use the EXTEST instruction to check the interconnection between chips, and can also use the INTEST instruction to test the internal logic of the chip.
By combining the BSDL and the design's "netlist", test applications can be automatically generated, which is particularly effective in high-end commercial JTAG test systems.
Such test systems can also benefit non-test-related applications, such as programming of various types of flash memory. As today's on-board components become increasingly dense, the existence of this technology is undoubtedly a great help to designers.
The Future of Boundary Scan
The potential for JTAG and boundary scan continues to grow. As the demands on embedded systems increase, the testing and debugging capabilities provided by boundary scan will become increasingly important. BSDL can not only enhance test coverage, but also accelerate product time to market and improve market competitiveness.
How many potential challenges are there in the field of electronic design waiting to be solved by boundary scan technology?
