Merge branch 'docs/mesh_channel_switch' into 'master'
docs: Add documentation about ESP-MESH channel switching and self organized behavior See merge request idf/esp-idf!3854
This commit is contained in:
Angus Gratton
commit
aae955d1ae
2 changed files with 370 additions and 625 deletions
File diff suppressed because it is too large
Load diff
|
|
@ -1,19 +1,19 @@
|
|||
ESP-MESH Programming Guide
|
||||
==========================
|
||||
|
||||
This is a programming guide for ESP-MESH, including the API reference and coding
|
||||
examples. This guide is split into the following parts:
|
||||
This is a programming guide for ESP-MESH, including the API reference and coding examples. This guide is split into the following parts:
|
||||
|
||||
1. :ref:`mesh-programming-model`
|
||||
|
||||
2. :ref:`mesh-writing-mesh-application`
|
||||
|
||||
3. :ref:`mesh-application-examples`
|
||||
3. :ref:`mesh-self-organized-behavior`
|
||||
|
||||
4. :ref:`mesh-api-reference`
|
||||
4. :ref:`mesh-application-examples`
|
||||
|
||||
For documentation regarding the ESP-MESH protocol, please see the
|
||||
:doc:`ESP-MESH API Guide<../../api-guides/mesh>`.
|
||||
5. :ref:`mesh-api-reference`
|
||||
|
||||
For documentation regarding the ESP-MESH protocol, please see the :doc:`ESP-MESH API Guide<../../api-guides/mesh>`.
|
||||
|
||||
|
||||
.. ---------------------- ESP-MESH Programming Model --------------------------
|
||||
|
|
@ -26,9 +26,7 @@ ESP-MESH Programming Model
|
|||
Software Stack
|
||||
^^^^^^^^^^^^^^
|
||||
|
||||
The ESP-MESH software stack is built atop the Wi-Fi Driver/FreeRTOS and may use
|
||||
the LwIP Stack in some instances (i.e. the root node). The following diagram
|
||||
illustrates the ESP-MESH software stack.
|
||||
The ESP-MESH software stack is built atop the Wi-Fi Driver/FreeRTOS and may use the LwIP Stack in some instances (i.e. the root node). The following diagram illustrates the ESP-MESH software stack.
|
||||
|
||||
.. _mesh-going-to-software-stack:
|
||||
|
||||
|
|
@ -42,10 +40,7 @@ illustrates the ESP-MESH software stack.
|
|||
System Events
|
||||
^^^^^^^^^^^^^
|
||||
|
||||
An application interfaces with ESP-MESH via **ESP-MESH Events**. Since ESP-MESH
|
||||
is built atop the Wi-Fi stack, it is also possible for the application to interface
|
||||
with the Wi-Fi driver via the **Wi-Fi Event Task**. The following diagram illustrates
|
||||
the interfaces for the various System Events in an ESP-MESH application.
|
||||
An application interfaces with ESP-MESH via **ESP-MESH Events**. Since ESP-MESH is built atop the Wi-Fi stack, it is also possible for the application to interface with the Wi-Fi driver via the **Wi-Fi Event Task**. The following diagram illustrates the interfaces for the various System Events in an ESP-MESH application.
|
||||
|
||||
.. figure:: ../../../_static/mesh-events-delivery.png
|
||||
:align: center
|
||||
|
|
@ -54,41 +49,19 @@ the interfaces for the various System Events in an ESP-MESH application.
|
|||
|
||||
ESP-MESH System Events Delivery
|
||||
|
||||
The :cpp:type:`mesh_event_id_t` defines all possible ESP-MESH system events and
|
||||
can indicate events such as the connection/disconnection of parent/child. Before
|
||||
ESP-MESH system events can be used, the application must register a **Mesh Event
|
||||
Callback** via :cpp:func:`esp_mesh_set_config`. The callback is used to receive
|
||||
events from the ESP-MESH stack as well as the LwIP Stack and should contain handlers
|
||||
for each event relevant to the application.
|
||||
The :cpp:type:`mesh_event_id_t` defines all possible ESP-MESH system events and can indicate events such as the connection/disconnection of parent/child. Before ESP-MESH system events can be used, the application must register a **Mesh Event Callback** via :cpp:func:`esp_mesh_set_config`. The callback is used to receive events from the ESP-MESH stack as well as the LwIP Stack and should contain handlers for each event relevant to the application.
|
||||
|
||||
Typical use cases of system events include using events such as
|
||||
:cpp:enumerator:`MESH_EVENT_PARENT_CONNECTED` and :cpp:enumerator:`MESH_EVENT_CHILD_CONNECTED`
|
||||
to indicate when a node can begin transmitting data upstream and downstream respectively. Likewise,
|
||||
:cpp:enumerator:`MESH_EVENT_ROOT_GOT_IP` and :cpp:enumerator:`MESH_EVENT_ROOT_LOST_IP` can be
|
||||
used to indicate when the root node can and cannot transmit data to the external IP
|
||||
network.
|
||||
Typical use cases of system events include using events such as :cpp:enumerator:`MESH_EVENT_PARENT_CONNECTED` and :cpp:enumerator:`MESH_EVENT_CHILD_CONNECTED` to indicate when a node can begin transmitting data upstream and downstream respectively. Likewise, :cpp:enumerator:`MESH_EVENT_ROOT_GOT_IP` and :cpp:enumerator:`MESH_EVENT_ROOT_LOST_IP` can be used to indicate when the root node can and cannot transmit data to the external IP network.
|
||||
|
||||
.. warning::
|
||||
When using ESP-MESH under self-organized mode, users must ensure that no calls
|
||||
to Wi-Fi API are made. This is due to the fact that the self-organizing mode
|
||||
will internally make Wi-Fi API calls to connect/disconnect/scan etc.
|
||||
**Any Wi-Fi calls from the application (including calls from callbacks and
|
||||
handlers of Wi-Fi events) may interfere with ESP-MESH's self-organizing behavior**.
|
||||
Therefore, user's should not call Wi-Fi APIs after :cpp:func:`esp_mesh_start`
|
||||
is called, and before :cpp:func:`esp_mesh_stop` is called.
|
||||
When using ESP-MESH under self-organized mode, users must ensure that no calls to Wi-Fi API are made. This is due to the fact that the self-organizing mode will internally make Wi-Fi API calls to connect/disconnect/scan etc. **Any Wi-Fi calls from the application (including calls from callbacks and handlers of Wi-Fi events) may interfere with ESP-MESH's self-organizing behavior**. Therefore, user's should not call Wi-Fi APIs after :cpp:func:`esp_mesh_start` is called, and before :cpp:func:`esp_mesh_stop` is called.
|
||||
|
||||
LwIP & ESP-MESH
|
||||
^^^^^^^^^^^^^^^
|
||||
|
||||
The application can access the ESP-MESH stack directly without having to go through
|
||||
the LwIP stack. The LwIP stack is only required by the root node to transmit/receive
|
||||
data to/from an external IP network. However, since every node can potentially
|
||||
become the root node (due to automatic root node selection), each node must still
|
||||
initialize the LwIP stack.
|
||||
The application can access the ESP-MESH stack directly without having to go through the LwIP stack. The LwIP stack is only required by the root node to transmit/receive data to/from an external IP network. However, since every node can potentially become the root node (due to automatic root node selection), each node must still initialize the LwIP stack.
|
||||
|
||||
**Each node is required to initialize LwIP by calling** :cpp:func:`tcpip_adapter_init`.
|
||||
In order to prevent non-root node access to LwIP, the application should stop the
|
||||
following services after LwIP initialization:
|
||||
**Each node is required to initialize LwIP by calling** :cpp:func:`tcpip_adapter_init`. In order to prevent non-root node access to LwIP, the application should stop the following services after LwIP initialization:
|
||||
|
||||
- DHCP server service on the softAP interface.
|
||||
- DHCP client service on the station interface.
|
||||
|
|
@ -111,11 +84,7 @@ The following code snippet demonstrates how to initialize LwIP for ESP-MESH appl
|
|||
|
||||
.. note::
|
||||
|
||||
ESP-MESH requires a root node to be connected with a router. Therefore, in
|
||||
the event that a node becomes the root, **the corresponding handler must start
|
||||
the DHCP client service and immediately obtain an IP address**. Doing so will
|
||||
allow other nodes to begin transmitting/receiving packets to/from the external
|
||||
IP network. However, this step is unnecessary if static IP settings are used.
|
||||
ESP-MESH requires a root node to be connected with a router. Therefore, in the event that a node becomes the root, **the corresponding handler must start the DHCP client service and immediately obtain an IP address**. Doing so will allow other nodes to begin transmitting/receiving packets to/from the external IP network. However, this step is unnecessary if static IP settings are used.
|
||||
|
||||
|
||||
.. ---------------------- Writing a Mesh Application --------------------------
|
||||
|
|
@ -125,9 +94,7 @@ The following code snippet demonstrates how to initialize LwIP for ESP-MESH appl
|
|||
Writing an ESP-MESH Application
|
||||
-------------------------------
|
||||
|
||||
The prerequisites for starting ESP-MESH is to initialize LwIP and Wi-Fi, The
|
||||
following code snippet demonstrates the necessary prerequisite steps before
|
||||
ESP-MESH itself can be initialized.
|
||||
The prerequisites for starting ESP-MESH is to initialize LwIP and Wi-Fi, The following code snippet demonstrates the necessary prerequisite steps before ESP-MESH itself can be initialized.
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
|
|
@ -148,8 +115,7 @@ ESP-MESH itself can be initialized.
|
|||
ESP_ERROR_CHECK(esp_wifi_set_storage(WIFI_STORAGE_FLASH));
|
||||
ESP_ERROR_CHECK(esp_wifi_start());
|
||||
|
||||
After initializing LwIP and Wi-Fi, the process of getting an ESP-MESH network
|
||||
up and running can be summarized into the following three steps:
|
||||
After initializing LwIP and Wi-Fi, the process of getting an ESP-MESH network up and running can be summarized into the following three steps:
|
||||
|
||||
1. :ref:`mesh-initialize-mesh`
|
||||
2. :ref:`mesh-configuring-mesh`
|
||||
|
|
@ -174,9 +140,7 @@ Configuring an ESP-MESH Network
|
|||
|
||||
.. todo - Add note about unified configuration
|
||||
|
||||
ESP-MESH is configured via :cpp:func:`esp_mesh_set_config` which receives its arguments
|
||||
using the :cpp:type:`mesh_cfg_t` structure. The structure contains the following
|
||||
parameters used to configure ESP-MESH:
|
||||
ESP-MESH is configured via :cpp:func:`esp_mesh_set_config` which receives its arguments using the :cpp:type:`mesh_cfg_t` structure. The structure contains the following parameters used to configure ESP-MESH:
|
||||
|
||||
+------------------+-------------------------------------+
|
||||
| Parameter | Description |
|
||||
|
|
@ -234,10 +198,118 @@ The following code snippet demonstrates how to start ESP-MESH.
|
|||
/* mesh start */
|
||||
ESP_ERROR_CHECK(esp_mesh_start());
|
||||
|
||||
After starting ESP-MESH, the application should check for ESP-MESH events to determine
|
||||
when it has connected to the network. After connecting, the application can start
|
||||
transmitting and receiving packets over the ESP-MESH network using
|
||||
:cpp:func:`esp_mesh_send` and :cpp:func:`esp_mesh_recv`.
|
||||
After starting ESP-MESH, the application should check for ESP-MESH events to determine when it has connected to the network. After connecting, the application can start transmitting and receiving packets over the ESP-MESH network using :cpp:func:`esp_mesh_send` and :cpp:func:`esp_mesh_recv`.
|
||||
|
||||
|
||||
.. --------------------- ESP-MESH Application Examples ------------------------
|
||||
|
||||
.. _mesh-self-organized-behavior:
|
||||
|
||||
Self Organized Networking
|
||||
-------------------------
|
||||
|
||||
Self organized networking is a feature of ESP-MESH where nodes can autonomously scan/select/connect/reconnect to other nodes and routers. This feature allows an ESP-MESH network to operate with high degree of autonomy by making the network robust to dynamic network topologies and conditions. With self organized networking enabled, nodes in an ESP-MESH network are able to carryout the following actions without autonomously:
|
||||
|
||||
- Selection or election of the root node (see **Automatic Root Node Selection** in :ref:`mesh-building-a-network`)
|
||||
- Selection of a preferred parent node (see **Parent Node Selection** in :ref:`mesh-building-a-network`)
|
||||
- Automatic reconnection upon detecting a disconnection (see **Intermediate Parent Node Failure** in :ref:`mesh-managing-a-network`)
|
||||
|
||||
When self organized networking is enabled, the ESP-MESH stack will internally make calls to Wi-Fi driver APIs. Therefore, **the application layer should not make any calls to Wi-Fi driver APIs whilst self organized networking is enabled as doing so would risk interfering with ESP-MESH**.
|
||||
|
||||
Toggling Self Organized Networking
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
Self organized networking can be enabled or disabled by the application at runtime by calling the :cpp:func:`esp_mesh_set_self_organized` function. The function has the two following parameters:
|
||||
|
||||
- ``bool enable`` specifies whether to enable or disable self organized networking.
|
||||
|
||||
- ``bool select_parent`` specifies whether a new parent node should be selected when enabling self organized networking. Selecting a new parent has different effects depending the node type and the node's current state. This parameter is unused when disabling self organized networking.
|
||||
|
||||
Disabling Self Organized Networking
|
||||
"""""""""""""""""""""""""""""""""""
|
||||
The following code snippet demonstrates how to disable self organized networking.
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
//Disable self organized networking
|
||||
esp_mesh_set_self_organized(false, false);
|
||||
|
||||
ESP-MESH will attempt to maintain the node's current Wi-Fi state when disabling self organized networking.
|
||||
|
||||
- If the node was previously connected to other nodes, it will remain connected.
|
||||
- If the node was previously disconnected and was scanning for a parent node or router, it will stop scanning.
|
||||
- If the node was previously attempting to reconnect to a parent node or router, it will stop reconnecting.
|
||||
|
||||
Enabling Self Organized Networking
|
||||
""""""""""""""""""""""""""""""""""
|
||||
|
||||
ESP-MESH will attempt to maintain the node's current Wi-Fi state when enabling self organized networking. However, depending on the node type and whether a new parent is selected, the Wi-Fi state of the node can change. The following table shows effects of enabling self organized networking.
|
||||
|
||||
+---------------+--------------+------------------------------------------------------------------------------------------------------------------+
|
||||
| Select Parent | Is Root Node | Effects |
|
||||
+===============+==============+==================================================================================================================+
|
||||
| N | N | - Nodes already connected to a parent node will remain connected. |
|
||||
| | | - Nodes previously scanning for a parent nodes will stop scanning. Call :cpp:func:`esp_mesh_connect` to restart. |
|
||||
| +--------------+------------------------------------------------------------------------------------------------------------------+
|
||||
| | Y | - A root node already connected to router will stay connected. |
|
||||
| | | - A root node disconnected from router will need to call :cpp:func:`esp_mesh_connect` to reconnect. |
|
||||
+---------------+--------------+------------------------------------------------------------------------------------------------------------------+
|
||||
| Y | N | - Nodes without a parent node will automatically select a preferred parent and connect. |
|
||||
| | | - Nodes already connected to a parent node will disconnect, reselect a preferred parent node, and connect. |
|
||||
| +--------------+------------------------------------------------------------------------------------------------------------------+
|
||||
| | Y | - For a root node to connect to a parent node, it must give up it's role as root. Therefore, a root node will |
|
||||
| | | disconnect from the router and all child nodes, select a preferred parent node, and connect. |
|
||||
+---------------+--------------+------------------------------------------------------------------------------------------------------------------+
|
||||
|
||||
The following code snipping demonstrates how to enable self organized networking.
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
//Enable self organized networking and select a new parent
|
||||
esp_mesh_set_self_organized(true, true);
|
||||
|
||||
...
|
||||
|
||||
//Enable self organized networking and manually reconnect
|
||||
esp_mesh_set_self_organized(true, false);
|
||||
esp_mesh_connect();
|
||||
|
||||
|
||||
Calling Wi-Fi Driver API
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
There can be instances in which an application may want to directly call Wi-Fi driver API whilst using ESP-MESH. For example, an application may want to manually scan for neighboring APs. However, **self organized networking must be disabled before the application calls any Wi-Fi driver APIs**. This will prevent the ESP-MESH stack from attempting to call any Wi-Fi driver APIs and potentially interfering with the application's calls.
|
||||
|
||||
Therefore, application calls to Wi-Fi driver APIs should be placed in between calls of :cpp:func:`esp_mesh_set_self_organized` which disable and enable self organized networking. The following code snippet demonstrates how an application can safely call :cpp:func:`esp_wifi_scan_start` whilst using ESP-MESH.
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
//Disable self organized networking
|
||||
esp_mesh_set_self_organized(0, 0);
|
||||
|
||||
//Stop any scans already in progress
|
||||
esp_wifi_scan_stop();
|
||||
//Manually start scan. Will automatically stop when run to completion
|
||||
esp_wifi_scan_start();
|
||||
|
||||
//Process scan results
|
||||
|
||||
...
|
||||
|
||||
//Re-enable self organized networking if still connected
|
||||
esp_mesh_set_self_organized(1, 0);
|
||||
|
||||
...
|
||||
|
||||
//Re-enable self organized networking if non-root and disconnected
|
||||
esp_mesh_set_self_organized(1, 1);
|
||||
|
||||
...
|
||||
|
||||
//Re-enable self organized networking if root and disconnected
|
||||
esp_mesh_set_self_organized(1, 0); //Don't select new parent
|
||||
esp_mesh_connect(); //Manually reconnect to router
|
||||
|
||||
|
||||
.. --------------------- ESP-MESH Application Examples ------------------------
|
||||
|
||||
|
|
@ -248,14 +320,9 @@ Application Examples
|
|||
|
||||
ESP-IDF contains these ESP-MESH example projects:
|
||||
|
||||
:example:`The Internal Communication Example<mesh/internal_communication>` demonstrates
|
||||
how to setup a ESP-MESH network and have the root node send a data packet to
|
||||
every node within the network.
|
||||
:example:`The Internal Communication Example<mesh/internal_communication>` demonstrates how to setup a ESP-MESH network and have the root node send a data packet to every node within the network.
|
||||
|
||||
:example:`The Manual Networking Example<mesh/manual_networking>` demonstrates
|
||||
how to use ESP-MESH without the self-organizing features. This example shows how
|
||||
to program a node to manually scan for a list of potential parent nodes and select
|
||||
a parent node based on custom criteria.
|
||||
:example:`The Manual Networking Example<mesh/manual_networking>` demonstrates how to use ESP-MESH without the self-organizing features. This example shows how to program a node to manually scan for a list of potential parent nodes and select a parent node based on custom criteria.
|
||||
|
||||
|
||||
.. ------------------------- ESP-MESH API Reference ---------------------------
|
||||
|
|
|
|||
Loading…
Reference in a new issue