nRF52840 Dongle Reset Issue

RE: nRF52840 Dongle Reset Issue

hmolesworth — Fri, 01 Mar 2019 16:06:22 GMT

You are welcome - and thanks for posting the great follow-up photos, they will help others :-)

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Fri, 01 Mar 2019 07:26:48 GMT

Hi,

[quote userid="65515" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173591"]1) FB2 has gone open-circuit, or got knocked off by the USB port plastic[/quote]

Excellent suggestion. That was it. The working dongle has the FB2:

..But the non-working one does not have the FB2 (maybe it is hard to see, but it is not there):

It must of fallen off.

per your suggestion, I shorted the USB GND and the GND edge connector. I couldn't quite bridge the FB2 just by soldering - little ugly, but this does the job:

...and now it is working!!! Thank you.

From the 2nd page and 3rd page of the schematic, it seems that if FB2 is gone, there is no USB GND connection to the rest of the board (except for the test pads in the back). So it makes sense that the side edge GND pins were not grounded.

BTW,

[quote userid="65515" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173591"]So where are you measuring the Gnd voltage and USB Gnd?[/quote]

I measured the USB GND like below:

and then the GND on the edge connectors.

Thank you for your help - and I appreciate your thorough explanation. I learned a lot.

Best Regards,

Mak

RE: nRF52840 Dongle Reset Issue

hmolesworth — Fri, 01 Mar 2019 04:22:32 GMT

Excellent! This raises two issues, 1) FB2 has gone open-circuit, or got knocked off by the USB port plastic, so just short it out and 2) how can the supply current be so high when there is no Gnd connection, which implies the warning is not about supply but about current through the signal + or -.

With no true Gnd the PRTR5V0U2X (D1) clamp will effectively short the inputs.

So where are you measuring the Gnd voltage and USB Gnd? edit: I see on the Gnd edge pin and I assume USB Gnd side? If so, then try shorting out FB2 which is really not required. The other possibility is the dongle is skewed so the VBUS makes contact but the Gnd does not, probably unlikely but not impossible; test by repeated inserts at different anlgles, and with a different USB port on the PC or Mac.

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Fri, 01 Mar 2019 02:14:42 GMT

Hi,

Thanks for the suggestion. I read the thread - maybe some pins could be receiving power when it is not supposed to? I commented on the other response below, but I'm seeing a strange fluctuating GND value (reading from the edge GND pins), when the debugger is not connected. Any suggestion for why that could be the case?

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Fri, 01 Mar 2019 02:06:55 GMT

Hi,

I've tried 2k and the computer (Mac) gave a warning dialog that it was drawing too much power. I've also tried 10k, and got a same overdraw response. No luck so far.

I am not using a coin cell - either from the computer or from a iPhone charger USB converter.

I noticed something interesting. The non-working Dongle's GND constantly fluctuates between 1~4v (relative to USB GND) when the debug probe is not connected (when it is not working). When I attach the debug probe (starts working), it shows 45mV (relative to USB GND). I'm measuring the GND reading from the edge connector's GND pins. The USB GND pin is stable, but the edge GND pins fluctuates (if debugger not connected)...why would that happen??

The working Dongle always have a GND around 1~20mV (relative to USB GND).

Any suggestions appreciated.

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

hmolesworth — Thu, 28 Feb 2019 15:37:06 GMT

Yes, that looks correct. maybe try with something like 2k or 10k .. this is my reasoning from the Errata document:

Workaround Do not draw current from VDD pin (external circuitry supply) during power up and ensure VDDH rise time to 3 V is below 1 ms.

Oh, and hopefully you are not using a coin cell or other high impedance power source? That would give a slow rise time .. USB stuff should be fine

RE: nRF52840 Dongle Reset Issue

Simonr — Thu, 28 Feb 2019 14:39:20 GMT

I can't seem to get a Dongle in the state yours is in. I did manage to get a fast blinking red LED, but I simply had to remove it from both debugger and USB port, then putting it back into the USB port to get it back to working normally.

I have however found a thread on the forum where someone with the nRF52832 DK had the same problem of the chip not working without the debugger. There are some tips here that could be worth testing on your Dongle as well. Please have a look, to see if anything helps. Starting to run short on ideas here.

Best of luck and kind regards,

Simon

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Thu, 28 Feb 2019 08:09:39 GMT

Hi,

I checked that both working one and non-working one are "QIAAC0".

[quote userid="65515" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173349"]or 100k resistor J2 pin 5 to pin 1 to bleed some current into Vdd..[/quote]

Ok. I tried it (hope I did it correctly):

...but no luck.

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Thu, 28 Feb 2019 08:01:32 GMT

Hi,

Thanks for the suggestion. I am using J2 with the tag-connect in circuit cable.

I tried soldering P1 pin10 to P1 pin 1, but no luck (did I test it correctly? see below pic). I think that will pull up the reset - the suspicion here is that the reset is somehow constantly bing pulled down, that it is trying to trigger reset all the time?

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

hmolesworth — Thu, 28 Feb 2019 01:07:43 GMT

Also are the two date codes on the nRF52840 dies identical? Reducing the load on VDD can help with this .. there is a load cap on RESET so if the RESET pin is disabled that may help .. or 100k resistor J2 pin 5 to pin 1 to bleed some current into Vdd..

POWER: Device does not start up in high voltage mode This anomaly applies to IC Rev. Rev 1, build codes QIAA-Cx0, CKAA-Cx0.

RE: nRF52840 Dongle Reset Issue

hmolesworth — Thu, 28 Feb 2019 00:53:03 GMT

Long shot .. are you using P1 or J2 to attach the debugger? If using P1, try with debugger removed and connect RESET P1 pin 10 to VDD_nRF P1 pin 1.

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Thu, 28 Feb 2019 00:38:45 GMT

Hi,

[quote userid="75734" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173178"]Can you walk me through how you tested for secure DFU OTA, so I can try to recreate the problem on my side?[/quote]

It was couple months ago, so I am not sure on the exact steps I took. I should have kept a log...

After trying out the secure DFU OTA, I didn't touch it until about a week ago, and found out something was not working right.

With that said, I recall first trying the one with "debug purpose only" secure BLE DFU example. After confirming that it worked, I followed the instructions listed in ble_sdk_app_dfu_bootloader to create my own signed firmware to flash. I was able to create a custom private/public key pair, and use the nRF Connect App for smartphone to flash it.

[quote userid="75734" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173178"]Please also refer to what firmware you used to flash it.[/quote]

Unfortunately I must have deleted the firmware I signed with my private key, as I can't locate it. I think it was the sample *.hex files that I used created the *.zip ...

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

Simonr — Wed, 27 Feb 2019 09:17:05 GMT

Can you walk me through how you tested for secure DFU OTA, so I can try to recreate the problem on my side? Please also refer to what firmware you used to flash it.

Best regards,

Simon

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Wed, 27 Feb 2019 03:25:32 GMT

Hi,

[quote userid="75734" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173038"]They both worked initially before the UICR erase am I right?[/quote]

Yes. Initially they both worked. Only the one that I re-flashed to test different DFU mode (was testing secure DFU OTA actually) is no longer working.

[quote userid="75734" url="~/f/nordic-q-a/44078/nrf52840-dongle-reset-issue/173038"]Have you checked that any of the solder bridges haven't been damaged or some components haven't been shorted by soldering paste?[/quote]

I have not made any modification physically to the dongle. To a naked eye it looks the same as the working one.

If I have the debugger connected, I can run the ble_app_blinky and debug (step it through) it after erasing the bootloader. If I flash the debug or release build on the dongle, it will work properly only if I have the debugger attached. It stops running when the debugger is removed.

Below is a summary of what I have tried with no boot loader, ble_app_blinky on the dongle.

If the dongle is connected to the computer and debugger is connected, it will function properly.
If the dongle is connected to the computer and debugger is not connected, it will not work.
If the dongle is not connected to the computer, and debugger connected, it will not work (it is not receiving power from the debugger).
If the dongle is connected to a USB power-only connection, and debugger connected, it will not work.

Maybe there is some issues with D+ and/or D- lines or its related circuitry. Would that matter in normal application execution (if it does not require UART type serial data)?

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

Simonr — Tue, 26 Feb 2019 13:08:39 GMT

The interface MCU solution I was wrong about, sorry for the confusion (It works on the 51 Dongle). This could seem like a hardware issue indeed. They both worked initially before the UICR erase am I right? It seems to me like the one not working was damaged somehow during the soldering process of resetting it. Have you checked that any of the solder bridges haven't been damaged or some components haven't been shorted by soldering paste?

Best regards,

Simon

RE: nRF52840 Dongle Reset Issue

makoto.inoue — Tue, 26 Feb 2019 01:34:23 GMT

Hi,

Thank you for the response.

I didn't have any user code flashed on the Dongle, just the MBR and Bootloader.

I tried the UICR erasing, then no LED comes on (and still not recognized by the nRF Connect Desktop app.

I then tried flashing the MBR+Bootloader hex file from the Dongle Programming Tutorial, but it still shows the same fast blinking red LED (and not in DFU mode) as soon as I remove the J-Link Plus debugger. I appears to work (goes into DFU mode) when the debugger is attached. When debug probe is attached, nRF Connect Desktop app recognizes the dongle.

I tried the Open Bootloader Example, and it appears to be in DFU mode (when debugger attached), but it would not work once I remove the J-Link Plus debugger.

The other possible solution you've mentioned links to the interface MCU firmware. I don't think the nRF52840 Dongle has an interface MCU.

I doubt the J-Link Plus debugger's firmware is the culprit here, as if that is the case the other dongle would fail too...

I will also note that I can flash user code (using nRF Connect Desktop), such as the ble_app_blinky and it will run - as long as the debug probe is connected.

It seems like a hardware issue...?

Thanks,

Mak

RE: nRF52840 Dongle Reset Issue

Simonr — Mon, 25 Feb 2019 14:00:16 GMT

What code/example do you have on the Dongle when fast blinking red LED is on?

I assume you have seen this Dongle Programming Tutorial, where the reset procedure is thoroughly explained. I urge you to try deleting the UICR and go through the reset process once more on the one not working to see if anything changes.

Another possible fix is resetting the MCU firmware following these steps:

1. Download MCU firmware from the link above (Should be a .bin file).

2. Plug in your dongle in bootloader mode (Holding the reset button while putting it into the USB port).

3. Copy the .bin file onto the device your device manager recognise as the Dongle.

4. The Dongle should start blinking faster when this is done, pull it out, then put it back in normally.

It should now pulsate again and work as normal.

Best regards,

Simon