Publishing Messages in Mesh Network

[rrwatt]

Hi guys,
I am attempting to modify the sensor-client/server model to create a mesh network of sensors that report to one client node. I am trying to use the esp_ble_mesh_model_publish method to publish a sensor's status to the client node once every few seconds. I am able to send messages using esp_ble_mesh_server_model_send_msg, but that will not work for me as my goal is to extend the range of the sparse network by propagating the message among servers until it reaches the client. Thus, I think I have to publish the message to a group address. I cannot figure out how to do this. For reference, I am using VSCode with ESP-IDF on Mac.

Here are my specific questions:
How and where do I create a publishing group?
How do I subscribe to this group on both the servers and the client?
How do I set the DST of the esp_ble_mesh_model_publish function and what should the parameters of that function be?
How do I handle the message on the client side?

As always, any help is greatly appreciated.

-rrwatt

[chegewara]

It is very simple, just compare both functions:

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esp_err_t esp_ble_mesh_server_model_send_msg(esp_ble_mesh_model_t *model,
                                             esp_ble_mesh_msg_ctx_t *ctx,
                                             uint32_t opcode,
                                             uint16_t length, uint8_t *data)
{
    if (model == NULL || ctx == NULL ||
        ctx->net_idx == ESP_BLE_MESH_KEY_UNUSED ||
        ctx->app_idx == ESP_BLE_MESH_KEY_UNUSED) {
        return ESP_ERR_INVALID_ARG;
    }

    return ble_mesh_model_send_msg(model, ctx, opcode, BTC_BLE_MESH_ACT_SERVER_MODEL_SEND,
                                   length, data, 0, false, ROLE_NODE);
}

Code: Select all

esp_err_t esp_ble_mesh_model_publish(esp_ble_mesh_model_t *model, uint32_t opcode,
                                     uint16_t length, uint8_t *data,
                                     esp_ble_mesh_dev_role_t device_role)
{
    if (model == NULL || model->pub == NULL || model->pub->msg == NULL ||
        model->pub->publish_addr == ESP_BLE_MESH_ADDR_UNASSIGNED) {
        return ESP_ERR_INVALID_ARG;
    }

    return ble_mesh_model_send_msg(model, NULL, opcode, BTC_BLE_MESH_ACT_MODEL_PUBLISH,
                                   length, data, 0, false, device_role);
}

Publish just ignore context, and you have to setup publish parameters on the model with provisioner like nrf mesh or other, which is setting up publish address.

[rrwatt]

Thanks for your quick response @chegewara. I am trying to send data from a sensor_server to all other nodes like this. Note that this code resides in the example_ble_mesh_send_sensor_status function.

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    ESP_LOG_BUFFER_HEX("Sensor Data", status, length);

    err = esp_ble_mesh_server_model_send_msg(param->model, &param->ctx,
            ESP_BLE_MESH_MODEL_OP_SENSOR_STATUS, length, status);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to send Sensor Status");
    }
    param->model->pub->publish_addr = 0xFFFF;
    err2 = esp_ble_mesh_model_publish(param->model, ESP_BLE_MESH_MODEL_PUBLISH_UPDATE_EVT, length, status, ROLE_NODE);
    
    ESP_LOGI(TAG, "Model Publish Addr: %u", param->model->pub->publish_addr);
    ESP_LOG_BUFFER_HEX("Message", param->model->pub->msg, length);

    err3 = esp_ble_mesh_model_publish(param->model, ESP_BLE_MESH_SENSOR_CLIENT_PUBLISH_EVT, length, status, ROLE_NODE);

    if(err2 != ESP_OK) {
        ESP_LOGE(TAG, "Failed to update. Error Code: %d", err2);
    }
    if(err3 != ESP_OK) {
        ESP_LOGE(TAG, "Failed to publish. Error Code: %d", err3);
    }

This is the output.

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I (110122) Sensor Data: c0 0a 17 60 0b 28 
I (110122) EXAMPLE: Model Publish Addr: 65535
I (110122) Message: 98 36 fc 3f 07 00 
W (110142) BLE_MESH: No outbound bearer found, inbound bearer 1
W (110152) BLE_MESH: No outbound bearer found, inbound bearer 1

First, I don't understand why Sensor Data doesn't match the Message field. Also, what is this warning message about outbound bearer? I thought that 0xFFFF refers to all nodes in the network, but when I try to handle the publish message in the client code, it acts like no message has been received and nothing happens. Any advice? Thanks in advance.

-rrwatt

[chegewara]

First, I don't understand why Sensor Data doesn't match the Message field. Also, what is this warning message about outbound bearer? I thought that 0xFFFF refers to all nodes in the network, but when I try to handle the publish message in the client code, it acts like no message has been received and nothing happens. Any advice? Thanks in advance.

-rrwatt

1. you get different values, because you are checking 2 different buffers
2. when you are sending to all nodes (0xffff) then it will be also send to all elements on the same node you are sending from, thats why you see this warning; consider its an info message

[rrwatt]

Oh, ok. I think I understand what you are saying. Also, to read the published message on the client node, can I just modify the

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example_ble_mesh_sensor_client_cb

function to handle a message inside the

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case ESP_BLE_MESH_SENSOR_CLIENT_PUBLISH_EVT

or do I need to write some new function to look for the published message? Right now no matter what I add inside the case it doesn't receive the message. Please let me know. Thanks.

-rrwatt

[chegewara]

Hi,
its not that i dont want to help you, but i believe it will be faster and with better results to you when you start from scratch.
- grab espressif example
- in custom callback (esp_ble_mesh_register_custom_model_callback) just print logs for event and opcode to see what you are receiving and to see what you have actually to pass in your own code

I will try to help you when you have more questions.

[LaithBlack]

create a mesh network of sensors that report to one client node.

Hello, could you share the project code, if possible. at my place of work, they decided to purchase esp 32 modules and set almost the same task as yours.