JTAG
Science & Engineering abbreviation · Electronics & Electrical
| Stands for | Joint Test Action Group |
|---|---|
| Categories | Science & Engineering |
JTAG stands for Joint Test Action Group, an electronics & electrical abbreviation.
Standard interface, IEEE 1149.1, for testing circuit board connections by "boundary scan" and for programming and debugging chips such as microcontrollers, processors and FPGAs through a few pins. Engineers use JTAG probes to step through firmware and inspect memory.
Example: Flash the new bootloader over JTAG if the board no longer boots from USB.
Usage notes
The Joint Test Action Group, an industry consortium formed in 1985, developed the method to test densely packed boards, and IEEE standardized it in 1990. Security researchers and hackers use exposed JTAG ports to extract firmware, so production devices often disable them. ARM's two-wire SWD is a common alternative.
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