Pairing only works when connected to RTT

RE: Pairing only works when connected to RTT

Sigurd Hellesvik — Mon, 25 Mar 2024 10:22:07 GMT

Hi mrd,

Håkon is on Easter Vacation, so you have two choices:

1. Wait until Håkon has returned.

2. Get help from me. In that case, I ask that you sum up this ticket briefly, so I can understand what it is about. Was the original issue that pairing does not work with RTT, or without RTT?
Does pairing work for all cases now, since you say you partially solved the issue?

[quote user="mrd"]My EEPROM thread has a positive priority (8) and waits on a queue[/quote]

Do you have k_sleep() in your application? Or is that question not relevant since you work with shell?

Regards,
Sigurd Hellesvik

RE: Pairing only works when connected to RTT

mrd — Fri, 22 Mar 2024 20:59:51 GMT

Hello Hakon,

This solves my problem! Thank you.

RE: Pairing only works when connected to RTT

helsing — Thu, 21 Mar 2024 12:02:48 GMT

Thank you for the update and for the reproducable example.

Check out this pull request which is likely causing this issue. You may cherry-pick the solution that is best for you.
https://github.com/zephyrproject-rtos/zephyr/pull/68941

RE: Pairing only works when connected to RTT

mrd — Wed, 20 Mar 2024 22:35:05 GMT

Hello Hakon,

I tried that (CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y) and it did not change anything.

I am happy to report that I have a minimum reproduceable example for you to try!

Minimum reproduceable example

For nrf52840 dk hardware.

Create a new application from nrf desktop sample in vscode.

Set up build configuration for nrf52840dk, prj_keyboard.conf, app.overlay.

Add following lines to prj_keyboard.conf

CONFIG_SHELL=y

CONFIG_SHELL_BACKENDS=y

CONFIG_SHELL_BACKEND_RTT=y

Erase and flash. Now pairing fails and no connection is made when RTT viewer is not connected.

If I change CONFIG_SHELL_BACKEND_RTT=n, pairing succeeds and the connection starts.

I've attached the support file with my versions of everything. Please try to reproduce this and let me know what you find.

Thank you!

devzone.nordicsemi.com/.../7723.version_5F00_info.txt

RE: Pairing only works when connected to RTT

helsing — Wed, 20 Mar 2024 12:01:46 GMT

Try configuring your project to use internal LF Oscillator. It should be straight forward to select this, however, I could update with the exact details later.

RE: Pairing only works when connected to RTT

mrd — Tue, 19 Mar 2024 21:31:53 GMT

Hello Hakon,

Any news? This bug cripples our product.

RE: Pairing only works when connected to RTT

mrd — Mon, 18 Mar 2024 22:14:27 GMT

Hi Hakon,

Something I just noticed: you don't need to be connected to RTT for a successful pairing. I only need to have connected to RTT.

If I flash my app, connect to RTT, disconnect from RTT, then pair, it works.

Additionally, we tried adding an inductor to one of our devboards, as indicated on page 31 here, but it did not fix the issue.

RE: Pairing only works when connected to RTT

mrd — Fri, 15 Mar 2024 18:32:08 GMT

Hello Hakon,

We are using a bootloader, as we are building on top of nrf desktop which uses a bootloader. When building nrf desktop with prj_keyboard.conf, it shows -Db0_CONF_FILE="C:/Users/mrdri/OneDrive/Documents/Work/CanAssist/Joystick/Joystick2/nrf_desktop_app/configuration/nrf52840dk_nrf52840/child_image/b0/prj.conf", so I added the two DCDC disable commands there.

A pristine build and flash later, I see the same behaviour.

I also created nrf_desktop_app/configuration/nrf52840dk_nrf52840/child_image/mcuboot.conf and added the disable commands there, as well as adding them to ....b0/prj_keyboard.conf, just in case, without effect.

Am I doing that properly?

I would also like to clarify what is not working to make sure we're on the same page: it's only the pairing/bonding process. If I connect to RTT, bond to a bt central device, then disconnect from RTT and power cycle our board, it will happily auto-reconnect to the the bonded device.

I've attached the gerbers for inspection.

Finally, I think it would be great once we solve this to remove our schematics/gerbers and make this case public again, in case anyone else has the same issue.

Thanks!

RE: Pairing only works when connected to RTT

helsing — Fri, 15 Mar 2024 15:32:23 GMT

We should look further into things regarding the DCDC.

When using RTT the SoC does not enter sleep, which will mask potential hardware issues. Several other customers report that things are running fine in debug mode and when RTT is connected you are continously debugging.

Are you using a bootloader? You would have to disable DCDC for the bootloader as well. Here is how to do so(from another ticket):

[quote userid="106736" url="~/f/nordic-q-a/92422/setting-config_bootloader_mcuboot-y-in-prj-config-on-custom-board-prevents-code-working/388708"]Create a folder in your project called child_image.
Then create the file child_image/mcuboot.conf.
Set the relevant configurations to disable DC-DC inside this mcuboot.conf as well.[/quote]

Thank you for sharing the schematic. Would you be able to share the Gerber files as well. We could check whether the layout might influence anything.

RE: Pairing only works when connected to RTT

mrd — Thu, 14 Mar 2024 16:30:55 GMT

Hi Hakon, thank you for the additional information.

Yes, I tested with those settings with the same results. I thought I'd include the build files on the off-chance that I was setting the DCDC converter to be disabled but it was not actually being disabled.

Also, I should note that when flashing and testing the board without RTT connected, the J-Link remains physically connected, just not in software. Would the grounding really change that much with the connection active or not?

For high-level design context, we are making a joystick that works over bluetooth.

RE: Pairing only works when connected to RTT

helsing — Thu, 14 Mar 2024 10:05:36 GMT

Hello mrd,

The issue you are seeing is typical for projects with grounding issues. When RTT is connected, there might be better grounding and the grounding issue potentially improved.

Has anyone at Nordic reviewed the schematic and layout? We can do this as a free service. I will make the case private in case you would like to upload the files.

[quote user="mrd"]

Edit: new build folder with CONFIG_BOARD_ENABLE_DCDC=n and CONFIG_BOARD_ENABLE_DCDC_HV=n

build_noDCDC.zip

[/quote]

I assume you have tested with these settings. Did you get the same results?

RE: Pairing only works when connected to RTT

mrd — Wed, 13 Mar 2024 05:19:33 GMT

Hello again Hakon,

I have tried CONFIG_BOARD_ENABLE_DCDC=n and CONFIG_BOARD_ENABLE_DCDC_HV=n, but it did not change behaviour.

I've attached the .conf file we are using.

Could you provide more information on what settings connecting to RTT changes in the background? Our symptoms are truly identical to the post that I linked to: it works when debugging or RTT connected.

Please note that this bug is striking at a terrible time - we must send our device in for RF testing in the next day or so. We do not need a fix, only a workaround - is there any way we can fool our chip into thinking it's connected to RTT, but not really be connected?

Any insight would be appreciated. Thank you.

devzone.nordicsemi.com/.../2117.prj_5F00_keyboard.conf

RE: Pairing only works when connected to RTT

mrd — Mon, 11 Mar 2024 17:31:24 GMT

Hi Hakon,

We are building nrf desktop for nrf52840 dk, using a modified prj_keyboard.conf. I downloaded the nrf desktop schematic files for the keyboard variant from here and it looks like keyboard example layout does have the DCDC converter components populated, which makes me think it's enabled.

For anyone seeing this in the future, where should I look to determine if DCDC is enabled in the build files? And how would I disable the DCDC converter, to make our design work for now?

Thank you for the help.

devzone.nordicsemi.com/.../5355.build.zip

Edit: new build folder with CONFIG_BOARD_ENABLE_DCDC=n and CONFIG_BOARD_ENABLE_DCDC_HV=n

devzone.nordicsemi.com/.../0131.build_5F00_noDCDC.zip

RE: Pairing only works when connected to RTT

helsing — Mon, 11 Mar 2024 10:07:09 GMT

Hello,

Would you be able to share your project's build folder? Which board are you building for? The idea is to check whether the DCDC is enabled in the build files and to see whether this is set in the board files.

Best regards,
Håkon