The Olimex ARM-JTAG-SWD has a 27 ohm resistor in series with the SRST line.
I’m using about a 3-inch ribbon cable between it and the board; the SWD
adapter is plugged directly into the JTAG-TINY, as they recommend.
Jay Maynard, K5ZC
http://plus.google.com/+JayMaynard
2018-02-24 12:48:23 +0000 Michael Schwingen <mich...@schwingen.org> :
> On Sat, 24 Feb 2018 00:52:44 +0100
> Tomas Vanek via OpenOCD-devel <openocd-devel@lists.sourceforge.net>
> wrote:
>
> On 24.02.2018 0:04, Jay Maynard wrote:
> More important is a small series resistor (33 ohm) on SWD - ringing
> prevention. Again not necessary if the cable to adapter is short.
>
>
> However, "short" may mean "really short" - I had signal integrity
> trouble doing SWD on a STM32 using a busblaster (FT2232 - my old version
> of the PCB has no series resistors on board), with 15cm cable. Adding
> series resistors to SWD and SWCLK fixed that.
>
> cu
> Michael
>
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