Hi Jehudi,

On Tue, Oct 17, 2017, Laczen JMS wrote:

Thanks for the response. I couldn't find CONFIG_BT_MESH_TX_SEG_COUNT
as configuration option, but I tried changing
CONFIG_BT_MESH_TX_SEG_MSG_COUNT which defaults to 1. I changed it to
10 but I am still getting the Not enough tailroom message. I am using
both 16k and 32k nrf51822, at the moment I am testing with the 32k
version.

Sorry, there's an internal define called BT_MESH_TX_SEG_COUNT, but it
actually gets its value from a different Kconfig variable. From the
transport.h header file:

#define BT_MESH_TX_SEG_COUNT (CONFIG_BT_MESH_ADV_BUF_COUNT - 3)
#define BT_MESH_TX_SDU_MAX (BT_MESH_TX_SEG_COUNT * 12)

So you'll want to increase CONFIG_BT_MESH_ADV_BUF_COUNT by 1 most
likely.

Johan

Hi Jehudi,

On Tue, Oct 17, 2017, Laczen JMS wrote:

I am trying to make a bluetooth mesh zephyr node with 2 elements.
After provisioning (which assigns 2 node adresses) meshctl ask for the
composition data. This fails with Not enough tailroom for TransMIC:

[bt] [DBG] dev_comp_data_get: (0x20001950) net_idx 0x0000 app_idx 0xfffe src 0x0
[bt] [ERR] bt_mesh_model_send: Not enough tailroom for TransMIC

What configuration option do I need to change (I am working on nrf51822) ?

I think you need to change CONFIG_BT_MESH_TX_SEG_COUNT. IIRC it defaults
to 3, and with your two elements you've created a composition data that
doesn't fit in three segments anymore. Increasing the SEG_COUNT to 4
will probably fix the issue. Note that this will also increase the
runtime memory consumption, so hopefully that doesn't go over your
limits (IIRC you had 16k?).

Johan