The Joint Test Action Group (JTAG) was founded in 1985, consisting of major electronics and semiconductor manufacturers, to promote a solution for the problem of board testing, which eventually resulted in the IEEE 1149.1-1990 standard.
JTAG is used to debug ARM chips by connecting to the Embedded ICE interface in the core. Many, but not all ARM chips, implement Boundary Scan as well for production tests. In most cases JTAG is also used to program the microcontrollers. High speed download is required for this option because it is part of the production flow.
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