NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

Marte Myrvold — Thu, 27 Nov 2025 12:05:28 GMT

Hi,

[quote user="begi_"]Messages are sent, although the nrf54l15DK crashed after 337 messages:[/quote]

Is this the same crash as you mentioned earlier in the ticket? I.e. this:

[quote user=""]However, if we use the same code/same build config with the NRF54L15DK, the ping sender crashes (Secure Fault) under heavy WiFi Interference.[/quote]

Does the nRF54L15 DK crash every time, and is it both the sender and receiver that crash, or only the sender?

Do you see any difference when testing the 802.15.4 PHY test tool with the nRF52840?

Best regards,
Marte

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

begi_ — Fri, 21 Nov 2025 08:47:42 GMT

[quote userid="148800" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/554357"]

Marte Myrvold said:

Do you see similar behavior with the IEEE 802.15.4 PHY test tool or Radio test (short-range) samples?

[/quote][quote userid="92402" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553836"]Do you see similar behavior with the IEEE 802.15.4 PHY test tool or Radio test (short-range) samples?[/quote]

I used the 802.15.4 PHY test tool and sent 500 rpings with different number of WiFi Interference Streams.
The PER seems to be roughly the same between the DK and PDK:

Although I'm not entirely sure how this test compares to the OpenThread measurement, as I am not quite aware of how the PHY/MAC differs (eg, number of retries)

We built the provided code for a nrf52840dk as well and repeated the test with different number of WiFi interference streams once more. This time we used a message length of 64. 470 Messages are sent, although the nrf54l15DK crashed after 337 messages:

The nrf52840 (green) performs as expected and similar to the nrf54l15pdk (blue). The nrf54l15dk (red) performs worse.

begi

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

begi_ — Fri, 14 Nov 2025 09:16:16 GMT

[quote userid="92402" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553836"]Is the code based on one of the SDK samples, and if so, which one?[/quote]

The code is based on the ot-cli example, extended with time sync and the pings. I attached the used code+prj.conf.

[quote userid="92402" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553836"]Can you debug the secure fault to gather more information about it? We have a lesson on debugging in our nRF Connect SDK Intermediate course on DevAcademy: Lesson 2 – Debugging and troubleshooting.[/quote]

Addr2Line reports:
addr2line -p -e build/thila2_test_node/zephyr/zephyr.elf 0x000955ae
/home/userxy/ncs/v3.1.1/modules/lib/openthread/src/core/common/message.hpp:461

message.hpp Line 461:

/**
* Returns the number of bytes in the message.
*
* @returns The number of bytes in the message.
*
*/
uint16_t GetLength(void) const { return GetMetadata().mLength; }

Stacktrace shows that the call comes from main -> otMessageAppend -> Messages::AppendBytes.
where it crashes on the first call of GetLength() on Line 406.
message.cpp:

Error Message::AppendBytes(const void *aBuf, uint16_t aLength)
{
    Error    error     = kErrorNone;
    uint16_t oldLength = GetLength();
 
    SuccessOrExit(error = SetLength(GetLength() + aLength));
    WriteBytes(oldLength, aBuf, aLength);
 
exit:
    return error;
}

In the disassembly (see red arrow) r0 (which is 0) is loaded with offset 34 (0x22) and therefore tries to read from 0x22 which lies in the secure partition:

[quote userid="92402" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553836"]Do you see similar behavior with the IEEE 802.15.4 PHY test tool or Radio test (short-range) samples?[/quote]

I will get back to this once I figure out a meaningful test

begi

devzone.nordicsemi.com/.../6874.main.c devzone.nordicsemi.com/.../43847.prj.conf

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

Marte Myrvold — Mon, 10 Nov 2025 14:18:27 GMT

Hi,

Is the code based on one of the SDK samples, and if so, which one?

Do you see similar behavior with the IEEE 802.15.4 PHY test tool or Radio test (short-range) samples?

Can you debug the secure fault to gather more information about it? We have a lesson on debugging in our nRF Connect SDK Intermediate course on DevAcademy: Lesson 2 – Debugging and troubleshooting.

Best regards,
Marte

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

begi_ — Wed, 05 Nov 2025 09:30:27 GMT

Thank you for the fast reply.

[quote userid="2111" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553294"]As far as I know, there is no board files for nRF54L15PDK in v3.1.1, so I am not entirely sure how you were able to test with the PDK? Can you elaborate how you solved this?[/quote]

As there were no explicit board files for the PDK, we assumed one can use the same as the DK. We used nrf54l15dk/nrf54l15/cpuapp/ns for both PDK and DK. Altough secure/nonsecure doesn't make a difference, see below

[quote userid="2111" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553294"]It could be interesting to see if this kconfig option have any effect on the problem you see.[/quote]

The issue still persists and the DK crashes regardless of CONFIG_SOC_NRF_FORCE_CONSTLAT with a Secure Fault if heavy interference is present.

[quote userid="2111" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference/553294"]Also, do you see the problem if you don't build for nrf54l15dk/nrf54l15/cpuapp/ns, but build for nrf54l15dk/nrf54l15/cpuapp/[/quote]

The problem persists if I use the secure build (I also tested both options for CONFIG_SOC_NRF_FORCE_CONSTLAT)

[quote userid="148800" url="~/f/nordic-q-a/125408/nrf54l15dk-vs-nrf54l15pdk-different-behaviour-of-openthread-exposed-to-wifi-interference"]Resistance to interference also appears to be lower, as indicated by a much higher PER for the DK compared to the PDK.[/quote]

Here is a comparison between the PDK and DK:
~470 Pings are sent with different Levels of WiFi Interference and the round trip time and PER are calculated.
As the observation period is very short, no "statistics" can be established, but it does show a trend of a worse performing PK.

begi

RE: NRF54L15DK vs NRF54L15PDK: Different behaviour of OpenThread exposed to WiFi Interference

Kenneth — Tue, 04 Nov 2025 12:05:59 GMT

Hello,

As far as I know, there is no board files for nRF54L15PDK in v3.1.1, so I am not entirely sure how you were able to test with the PDK? Can you elaborate how you solved this?

In general though the old nRF54L15PDK did have a workaround that prevented low power mode, this was set by this kconfig option:
CONFIG_SOC_NRF_FORCE_CONSTLAT=y
(see: https://github.com/nrfconnect/sdk-zephyr/blob/v3.6.99-ncs2/boards/nordic/nrf54l15pdk/nrf54l15pdk_nrf54l15_cpuapp_defconfig#L28)

It could be interesting to see if this kconfig option have any effect on the problem you see.

Also, do you see the problem if you don't build for nrf54l15dk/nrf54l15/cpuapp/ns, but build for nrf54l15dk/nrf54l15/cpuapp/

Kenneth