NCS Mesh: Transferring Composition Data fails

[mesh777]

We have relatively big model composition, and reading it via nRF Mesh app fails if it exceeds 21 segment message.

However the limit I assume should be at 32 segments and is set by CONFIG_BT_MESH_TX_SEG_MAX. Also I set CONFIG_BT_MESH_ADV_BUF_COUNT to be larger than TX_SEG_MAX by 3 as specified in its description.

Is there any other limitations for composition size?

I am using nRF Connect SDK v1.7.

[Mttrinh]

Hi,

Currently only one composition data page is described in the mesh specification, and so if you put too much on the device then you will exceed the available space for composition data. The spec mentions more composition pages, but unfortunately they are only reserved for future use

Mesh Profile Specification v1.0.1 section 4.2.1 Composition Data. The size of the composition data pages are restricted to the maximum useful access payload size of 376 octets, and composition data page 0 should contain, among other things, element descriptions.

[Mttrinh]

Hi,

Are you receiving any error code on the nRF side?

[Mttrinh]

Hi,

There was Bluetooth Host bug for authentication frames with data larger than 255 bytes. This is fix in upstream: https://github.com/zephyrproject-rtos/zephyr/pull/45232

Timeout is also possible since default configuration client timeout doesn't consider large composition data. This PR allows to tune timeout:
https://github.com/zephyrproject-rtos/zephyr/pull/44825

You can apply changes from these PRs to your project. Unfortunately both PRs are on upstream and will be available in NCS repo after next upmerge.

[mesh777]

Hi, Mttrinh. Thanks for the provided solution.

Will these bugs be fixed in the next SDK release?

[Mttrinh]

Hi,

The fixes are in downstream already, in zephyr-v3.1.0. You can check yourself in your version by calling this:

git show 0aa0913ca5d6ca1708b720d28ade8c99a16a416c
git show dbc76894049660b007342b8b33fb2dab45980186

[mesh777]

Hi Mttrinh,

I do not see this fix in a list of addressed issues of Zephyr 3.1.0 documentation.

Also is there available table of Zephyr version used in particular NCS version, so I can check which NCS version contains e.g. Zephyr 3.1.0.

[tesc]

Hi,

The fixes were merged to the Zephyr project through the following pull requests, about half a year ago:

• https://github.com/zephyrproject-rtos/zephyr/pull/45232
• https://github.com/zephyrproject-rtos/zephyr/pull/44825

I am however unable to find any mention of those fixes in the release notes, just as you are.

There is no table of nRF Connect SDK to Zephyr version mapping, but the nRF Connect SDK release notes list the upstream Zephyr commit, as can be seen e.g. for the current main branch of nRF Connect SDK: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/releases/release-notes-changelog.html#zephyr

You can also deduce Zephyr version from the Zephyr Project documentation hosted on developer.nordicsemi.com, where there is a drop-down in the top right corner of the page for selecting nRF Connect SDK version.

Regards,
Terje

[mesh777]

Hello, provided fix seems to solve the issue, thank you.

However I am getting warning "W: No matching TX context for ack". What it actually means and how to resolve it?

My Mesh buffers are configured with following:

CONFIG_BT_MESH_ADV_BUF_COUNT=35
CONFIG_BT_MESH_TX_SEG_MAX=32
CONFIG_BT_MESH_RX_SEG_MAX=32
CONFIG_BT_MESH_PB_GATT=y
CONFIG_BT_MESH_PB_ADV=y
CONFIG_BT_MESH_TX_SEG_MSG_COUNT=5

I have tried to increase ADV_BUF_COUNT to 45 and TX_SEG_MSG_COUNT to 7 but that did not help.