External Jlink is not working

[Deepa Gopinath]

Hi all,

We have custom board which has On Board Jlink support with nRF52832 using STM32 chip(STM32F072CBT6).

We are able to flash and debug using the On Board Jlink.

Now we are planning to use external Jlink (Jlink 9.3) to flash and debug on nRF52832 Chip.

We have pulled out SWDIO, SWCLK, VTargetRef and Gnd pins on nRF52832 Chip and then connected to External Jlink (Jlink 9.3). 

With External Jlink, we are unable to connect to  nRF52832 Chip.and observed the issue "Cannot connect to target"

On segger embedde studio, if we try to connect we got an error - "Failed to connect to target, no Idcode detected"

Please find the attached log files for more details

Thanks in Advance

Regards,

Deepa

Jlink_Issue.zip

[awneil]

Are you sure it's not your "STM32 chip" interfering with the external J-Link ?

https://wiki.segger.com/J-Link_cannot_connect_to_the_CPU

[vg7190]

Hi awneil thanks for your response.

Currently after connecting external jLink to pulled out pins. I am still able to use the on board jLink.

Is there a chance that it is causing an issue?

I suspect it after going through the following line from the wiki page,

• Disconnect on board emulators or other peripherals which may interact on the target interface lines

if so, do I need to disconnect only 4 lines e.g. CLK, DIO, GND, Vref or I should disconnect other peripheral also such as UART which is also connected to same line.

[awneil]

vg7190 said:

after connecting external jLink to pulled out pins. I am still able to use the on board jLink

vg7190 said:

Is there a chance that it is causing an issue

I'd say that's (almost) certain!

The SWD interface is not a bus - it is not designed to be shared!

vg7190 said:

do I need to disconnect only 4 lines e.g. CLK, DIO, GND, Vref

Assuming that those are the only lines that your "external jLink" uses - yes.

(there are many different models of J-Link - some have more features than others)

vg7190 said:

I should disconnect other peripheral also such as UART which is also connected to same line.

What do you mean, "connected to same line" ?

Take a look at the Nordic DK schematics to see how they do it ...

[awneil]

awneil said:

Take a look at the Nordic DK schematics to see how they do it

Also, as you're using STM32, take a look at how ST do it on their Nucleo & Discovery boards - which also have an onboard debug probe (ST-Link, in their case), plus support for an external debugger ...

This really isn't specific to Nordic - it's general SWD stuff.