The nRF51 also (strangely!) has a non standard SWD interface. It's the
first time I've come across that, and I'm not sure what the thinking
behind multiplexing RST with the SWD pins was (extremely low pin count
devices?), but it breaks the normal behaviour of SWD on ARM Cortex M and
you need to handle it as an edge case on the J-Link and other debuggers
internally. Thankfully, the nRF52 doesn't have this same 'feature', and
the peripherals are all around more pleasant to use. :)
On 22/11/16 18:23, Wayne Keenan wrote:
Do you have any other devices connected to your nRF (electronically, not
BLE) and are actively trying to send data to the nRF?
If so, detach them and try again.
In one repeatable case I've found it impossible to connect to an nRF51
using SWD via the J-Link when another MCU was communicating using SPI to
the nRF51.
This happened even if the nRF was totally erased, the SPI chatter just got
in the way of SWD working.
ymmv
All the best
Wayne
On 22 November 2016 at 17:07, David G. Simmons <[email protected]> wrote:
How are you keeping the board in reset? The only method I've found is to
power the board off, and so far, my timing has not paid off on that front.
dg
On Nov 22, 2016, at 12:04 PM, marko kiiskila <[email protected]> wrote:
Hi,
my trick with this is by keeping the board in reset just until I start
the
JTAG software. This might take few attempts, but I eventually get lucky
with timing, and MCU stops before system boots.
--
David G. Simmons
(919) 534-5099
Web <https://davidgs.com/> • Blog <https://davidgs.com/davidgs_blog> •
Linkedin <http://linkedin.com/in/davidgsimmons> • Twitter <
http://twitter.com/TechEvangelist1> • GitHub <http://github.com/davidgs>
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