Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Tue, 06 May 2025 11:02:18 GMT

What is important is that you are as close to the pads as possible without anything in between that could possibly affect the SWD signals somehow.

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Wed, 30 Apr 2025 08:18:34 GMT

Hi,

I didn't solder directly to our board, as the pads are tiny, but I used PCBite SP10 probes, and this worked flawlessly. It shouldn't make a difference whether I solder wires onto the PCB or probe it, should it?

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Tue, 22 Apr 2025 10:26:14 GMT

Hi,

When connecting directly to the board, did you solder wires to the SWD pads? Can you explain in more detail how you did this?

regards

Jared

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Thu, 17 Apr 2025 13:31:11 GMT

Hi,

i thought it could be the switch as well, but when I desoldered it and just connected the lines directly it didn't work either.

Great question, but unfortunately I've tried it with many boards, none worked.

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Mon, 07 Apr 2025 11:20:05 GMT

Hi,

As you have described it, this issue is very strange.

If you can program the board once you connect directly to the pads then we can assume that this issue is external to the chip. What exactly is causing this is not easy to say, could this be caused by the programming switch somehow?

I don't think it has already been mentioned but do you see this issue on multiple boards or only 1?

regards

Jared

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Fri, 04 Apr 2025 07:27:15 GMT

Thanks for your reply. I thoroughly tested every pin for a short - to no avail. Yes we're using a battery, but I also tried supplying the board with 5V via USB, still doesn't work.

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Hung Bui — Fri, 28 Mar 2025 12:12:02 GMT

Hi Lepold,
Jared is away this week and will be back next week.
My understanding is that when you connect the programmer to the board with cable instead of connecting directly to the header it worked.
You would need to take a deeper look into the header you use. Is there any chance that something is shorted ?
Test on all single pin to see if any thing is shorted.
My personal experience with SWD is that it's not a high speed communication so it's quire resilient to interference so more chance that there is something shorted somehow.
Please also try supply the board/chip with external power supply. I assume you are using a battery ?

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Tue, 25 Mar 2025 13:19:10 GMT

Thank you for the clarification! When connecting to the SWD pads directly, I can consistently program the chip. I can't really provide you with traces, because as soon as I probe the line, it doesn't work program anymore..

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Fri, 14 Mar 2025 14:22:41 GMT

Hi,

I'm sorry for the confusion. To be clear, I'm interested in knowing whether this is an issue with your PCB design or it's an issue with the IC itself. Based on your description, it seems like the issue is due to PCB design, but to be sure I wanted you to connect directly to the SWD pads and see if you are able to program the chip consistently .

It would also be interesting if you could provide trace of SWDIO, and SWDCLK when it works versus when it doesn't work. Is there any obvious change in the CLK or data signal?

regards

Jared

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Thu, 13 Mar 2025 16:37:23 GMT

I'm not sure I'm correctly understanding what you're referring to. Soldering wires to the nRF5340 directly onto the debugging PCB? Or trying whether I can program it at all? Because this works, just not with this custom PCB. Could you please clarify what I can try? Thank you!

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Wed, 12 Mar 2025 13:31:23 GMT

Hi,

Can you try to solder some wires that is connected directly to the pads of the nRF5340 + VDD and GND and see if you are able to program it?

regards

Jared

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Fri, 07 Mar 2025 11:01:50 GMT

We can keep this public, it's an open source project anyway. I've attached the schematics and gerber files. Please let me know when you need anything else. The board we're trying to flash also has a DSP, that's why we have this switch on the debugging PCB. But that should not cause any problems, right?

devzone.nordicsemi.com/.../Debugging_5F00_PCB.zip

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

Jared — Fri, 07 Mar 2025 10:41:56 GMT

Hi,

Could you share the schematics and layout files? You can share it as a PDF and Gerber files.

I can make the case private first if you prefer it.

regards

Jared

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

lepold — Fri, 07 Mar 2025 09:41:32 GMT

I've tried different programmers to no avail, but we only have EDU programmers because I'm working at a university. JLink shows VTref=1.812V, both on the older debugging PCB that works, and on the new PCB design that doesn't work. I also tried J-Link EDU Mini V2 with jumper wires: here the debugging PCB doesn't work either, whereas with the "normal" J-Link EDU it works with the exact same cables etc.

RE: Programming Custom nRF5340 PCB via J-Link Interface defies laws of physics?

d2sc — Thu, 06 Mar 2025 17:23:32 GMT

Have you tried with a different programmer? What is the voltage Jlink is reporting from the target device? I have had issues with the edu programmers before that went away when I switched to the commercial ones.