It is possible to create a client application using lightness_client model to control lightness_server device.
But, for implementing your project for street lights, I believe dimmer and light_dimmable applications are sufficient, unless you want to use all the features and messages defined in light_lightness model. Please check the spec https://www.bluetooth.com/specifications/mesh-specifications/.
Here, Dimmer app implements WICED_BT_MESH_MODEL_LEVEL_CLIENT model and light_dimmable app implements WICED_BT_MESH_MODEL_LIGHT_LIGHTNESS_SERVER model (It also implements all the dependent and mandatory models as per mesh spec). Since Light Lightness Actual state is bound to Generic Level state, we will be able to control the light (LED) associated with the light_dimmable app.
The latest Modustoolbox supports CYW20706 also. I would suggest you to migrate to Modustoolbox and continue developing your application.
wiced_bt_mesh_model_level_client_set is another API to create appropriate mesh event and send the level_set message to the destination. This API is available from WICD6.4 onward. Please check wiced_bt_mesh_models.h for the description of wiced_bt_mesh_model_level_client_send_set API.
Please let me know if you have questions.
Thank you for sharing the information. i will get back to you for further queries after exploring WICED 6.4 and modbus.
I have tried wiced_bt_mesh_model_light_lightness_client_send_set to send messages to other server node but could not find proper p_event argument value, so it failed. What is the light lightness client's API function to send messages to light lightness server?