Bluetooth Mesh - When associating a vendor model to an Element, the Nordic Mesh App fails to retrieve the models if there are more than one model.

Question

When creating a Bluetooth Mesh Vendor model ( https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/protocols/bt/bt_mesh/vendor_model/dev_overview.html ) and if the vendor model is associated to the first element: 
 
 static const struct bt_mesh_elem elements [] = { 
 BT_MESH_ELEM ( 0 , root_models , vnd_sampleModel ), 
 //BT_MESH_ELEM(1, sensrvModel, BT_MESH_MODEL_NONE ), // For some reason enabling further Models makes the NRF app unable to get the models. 
 }; 
 
 The Mesh App works fine and can retrieve the node available models, including the vendor one, and work with it. The same is true if instead of vnd_sampleModel it is replaced by the standard BT_MESH_MODE_NONE. So nothing new here. 
 The issue arises, if, for example, on the above case the Element 1 is activated. If Element 0, has the vendor model set as none, the Mesh app works fine and can retrieve both Element 0 and Element 1. 
 If however the vendor model is declared either on the Element 0 or Element 1, the Mesh app fails to retrieve the available models.

Amanda Hsieh · Answer

Hi, I can reproduce the issue with your modification and see the following debug log : Mesh initialized [00:00:01.709,503] bt_l2cap: bt_l2cap_recv: Ignoring data for unknown channel ID 0x003a [00:00:06.489,227] bt_mesh_access: bt_mesh_model_recv: app_idx 0xfffe src 0x0001 dst 0x0003 [00:00:06.489,288] bt_mesh_access: bt_mesh_model_recv: len 3: 800800 [00:00:06.489,288] bt_mesh_access: bt_mesh_model_recv: OpCode 0x00008008 [00:00:06.489,318] bt_mesh_access: comp_add_elem: Too large device composition [00:00:06.489,349] bt_mesh_cfg_srv: dev_comp_data_get: Failed to get CDP0, err:-7 This means, the max TX segment configuration is not correct, and thus there are not enough buffers to store bigger composition data. Please try to set CONFIG_BT_MESH_TX_SEG_MAX=5 to allow transmissions of messages up to 5 segments long to solve the problems. After adding this config, I see this issue goes away with the Android app on my side. -Amanda H.

Bluetooth Mesh -> When associating a vendor model to an Element, the Nordic Mesh App fails to retrieve the models if there are more than one model.

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