ESL Tutorial - Unexplained byte in responses

RE: ESL Tutorial - Unexplained byte in responses

Amanda Hsieh — Thu, 06 Nov 2025 19:50:20 GMT

The latest issue is away from the original scope. Please create a new support case. Thanks.

RE: ESL Tutorial - Unexplained byte in responses

Scott Grubb — Thu, 06 Nov 2025 17:16:26 GMT

Hi Amanda,

Thanks again for your help with all of these ESL questions. I had disabled the unused peripherals as per the guide but the problem turned out to be an external sensor that was being initialised too soon after power-on. It's now working.

I'm now trying to adjust the PaWR timing parameters but I don't seem to be able to adjust the Subevent Interval below 8 without causing the Central ESL app to stop working. For example, the following works:

CONFIG_ESL_PAWR_INTERVAL_MIN=1024

CONFIG_ESL_PAWR_INTERVAL_MAX=1024

CONFIG_ESL_CLIENT_MAX_GROUP=128

CONFIG_ESL_SUBEVENT_INTERVAL=8

CONFIG_ESL_RESPONSE_SLOT_DELAY=4

CONFIG_ESL_RESPONSE_SLOT_SPACING=2

CONFIG_ESL_NUM_RESPONSE_SLOTS=8

CONFIG_ESL_CLIENT_MAX_RESPONSE_SLOT_BUFFER=8

but this doesn't:

CONFIG_ESL_PAWR_INTERVAL_MIN=768

CONFIG_ESL_PAWR_INTERVAL_MAX=768

CONFIG_ESL_CLIENT_MAX_GROUP=128

CONFIG_ESL_SUBEVENT_INTERVAL=6

CONFIG_ESL_RESPONSE_SLOT_DELAY=4

CONFIG_ESL_RESPONSE_SLOT_SPACING=2

CONFIG_ESL_NUM_RESPONSE_SLOTS=8

CONFIG_ESL_CLIENT_MAX_RESPONSE_SLOT_BUFFER=8

I can't see anything obvious in the central_esl code but I thought that maybe CONFIG_ESL_SUBEVENT_INTERVAL was being divided by 8 somewhere which was causing values less than 8 to result in an error. There are no clues in the log, because when the problem occurs, it also stops the VCP from working.

Regards

Scott

RE: ESL Tutorial - Unexplained byte in responses

Amanda Hsieh — Fri, 31 Oct 2025 19:15:28 GMT

Hi,

[quote user="Scott Grubb"]I've disabled all unused peripherals on the tag (including the UART) [/quote]

How did you disable the unused peripherals? Did you refer to the Disable unused pins and peripherals?

RE: ESL Tutorial - Unexplained byte in responses

Scott Grubb — Fri, 31 Oct 2025 16:19:23 GMT

Thanks again. One other question related to ESL/PAwR: do you know how the tags were configured to obtain the power consumption figures shown here: (+) Periodic Advertising with Responses (PAwR): A practical guide - Software - nRF Connect SDK guides - Nordic DevZone?

I've disabled all unused peripherals on the tag (including the UART) but am struggling to get the power consumption down to anything like these levels when running the ESL demo. The lowest I have achieved so far using the default PaWR timing parameters is around 170uA.

Thanks

Scott

RE: ESL Tutorial - Unexplained byte in responses

Amanda Hsieh — Wed, 29 Oct 2025 16:57:35 GMT

It's defined in https://bitbucket.org/bluetooth-SIG/public/src/8c192a8effd1574d0c83e72ad91407511bcad209/assigned_numbers/core/ad_types.yaml#lines-179,180,181

RE: ESL Tutorial - Unexplained byte in responses

Scott Grubb — Tue, 28 Oct 2025 18:00:54 GMT

Hi,

Thanks for this. That explains it! Do you happen to know if this is something particular to Nordic's implementation of ESL? I don't think it's mentioned in the ESL Service documentation (but I might have missed it there too).

Scott

RE: ESL Tutorial - Unexplained byte in responses

Amanda Hsieh — Fri, 24 Oct 2025 13:21:26 GMT

Hi,

Check the 1- Nordic Bluetooth ESL Tutorial v0.9.1.pdf in the Downloaded kit (here), page. 25:

Regards,
Amanda H.