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Is JTAG faster than SWD?

j3lda
Associate II
Posted on June 13, 2013 at 11:33

Hello, is JTAG faster than SWD? Thank you very much for answer.

2 REPLIES 2
Posted on June 13, 2013 at 11:51

At doing what?

SWD is pretty useless for doing boundary scan.

Programming/Erasing flash tends to be bounded by the performance of the array.
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jj2
Associate II
Posted on June 13, 2013 at 17:06

From memory - past read (on ARM's site) that during debug/programming - the newer SWD is faster than JTAG.  (and indeed - suffers the limitation Clive mentions)

Using paid IAR - we've noted ~ 10-15% faster code downloads (>200KB) when switching from JTAG to SWD.  (using JLink - all else held as consistent as possible)

SWD switches the single data line between transmit & receive - thus may suffer when large data reads from the MCU are required...

And - 2 of the JTAG pins may be ''harvested'' for use as GPIO - when SWD is chosen...