BSDL File

What are BSDL files and how to open them

Are you having problems opening a BSDL file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BSDL files.

What is a BSDL file?

A .BSDL file is a Boundary Scan Description Language file.

Boundary Scan Description Language provides a way for manufacturers of digital chips to describe how the boundary-scan (JTAG) test functionality is implemented in a particular device. The file holds the needed test architecture information so that automated test tools, in-system programming systems, or boundary-scan test vector generators can prepare correct tests and control signals for that device. It reports how many pins or balls are involved, what scan-registers the chip supports, what instructions the chip understands for testing, and how the external pins map to internal stimulus and observation points.

The language was developed by the IEEE working group and is specified in IEEE Std 1149.1 (and successive revisions) as Annex B. Its syntax is defined as a constrained subset of VHDL (Very High Speed Integrated Circuits Hardware Description Language), with added reserved keywords and attributes for boundary-scan behavior. Chip manufacturers write the BSDL file when creating any device that includes IEEE-1149.1 boundary-scan support; test tool suites or programmers read it to know how to exercise test or programming features on that device. The file is human-readable text and can be opened in any text editor.

Technical identifiers inside the data include attributes such as INSTRUCTION_LENGTH, BOUNDARY_REGISTER, REGISTER_ACCESS, PIN_MAP or PHYSICAL_PIN_MAP, and include keywords for instructions like BYPASS, EXTEST, SAMPLE, etc. A typical file starts with the entity declaration (often "entity <component name> is"), followed by sections for ports, generics, instruction register description, and the boundary-scan register description. Because BSDL is based on VHDL syntax, identifiers, strings, comments, delimiters, reserved words follow VHDL-like lexical rules. Byte-signatures of some files may include the ASCII sequence "entity" at offset 0, and strings such as ATTRIBUTE INSTRUCTION_LENGTH, ATTRIBUTE BOUNDARY_REGISTER, ATTRIBUTE PIN_MAP, etc.

How to open BSDL files

Important: Different programs may use files with the BSDL file extension for different purposes, so unless you are sure which format your BSDL file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 25, 2026

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