OVMS3-idf/docs/en/api-reference/mesh/esp_mesh.rst
Darian Leung f4c3917712 docs/rewrite_mesh_docs
The following commit rewrites the ESP-MESH docs. This commit includes
new diagrams and a structure approach to the mesh docs. Some mesh api references
have also been modified.
2018-09-02 21:34:21 +08:00

268 lines
9.9 KiB
ReStructuredText

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:
1. :ref:`mesh-programming-model`
2. :ref:`mesh-writing-mesh-application`
3. :ref:`mesh-application-examples`
4. :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 --------------------------
.. _mesh-programming-model:
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.
.. _mesh-going-to-software-stack:
.. figure:: ../../../_static/mesh-software-stack.png
:align: center
:alt: ESP-MESH Software Stack
:figclass: align-center
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.
.. figure:: ../../../_static/mesh-events-delivery.png
:align: center
:alt: ESP-MESH System Events Delivery
:figclass: align-center
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.
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.
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.
**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.
The following code snippet demonstrates how to initialize LwIP for ESP-MESH applications.
.. code-block:: c
/* tcpip initialization */
tcpip_adapter_init();
/*
* for mesh
* stop DHCP server on softAP interface by default
* stop DHCP client on station interface by default
*/
ESP_ERROR_CHECK(tcpip_adapter_dhcps_stop(TCPIP_ADAPTER_IF_AP));
ESP_ERROR_CHECK(tcpip_adapter_dhcpc_stop(TCPIP_ADAPTER_IF_STA));
/* do not specify system event callback, use NULL instead. */
ESP_ERROR_CHECK(esp_event_loop_init(NULL, NULL));
.. 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.
.. ---------------------- Writing a Mesh Application --------------------------
.. _mesh-writing-mesh-application:
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.
.. code-block:: c
tcpip_adapter_init();
/*
* for mesh
* stop DHCP server on softAP interface by default
* stop DHCP client on station interface by default
*/
ESP_ERROR_CHECK(tcpip_adapter_dhcps_stop(TCPIP_ADAPTER_IF_AP));
ESP_ERROR_CHECK(tcpip_adapter_dhcpc_stop(TCPIP_ADAPTER_IF_STA));
/* do not specify system event callback, use NULL instead. */
ESP_ERROR_CHECK(esp_event_loop_init(NULL, NULL));
/* Wi-Fi initialization */
wifi_init_config_t config = WIFI_INIT_CONFIG_DEFAULT();
ESP_ERROR_CHECK(esp_wifi_init(&config));
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:
1. :ref:`mesh-initialize-mesh`
2. :ref:`mesh-configuring-mesh`
3. :ref:`mesh-start-mesh`
.. _mesh-initialize-mesh:
Initialize Mesh
^^^^^^^^^^^^^^^
The following code snippet demonstrates how to initialize ESP-MESH
.. code-block:: c
/* mesh initialization */
ESP_ERROR_CHECK(esp_mesh_init());
.. _mesh-configuring-mesh:
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:
+------------------+-------------------------------------+
| Parameter | Description |
+==================+=====================================+
| Channel | Range from 1 to 14 |
+------------------+-------------------------------------+
| Event Callback | Callback for Mesh Events, |
| | see :cpp:type:`mesh_event_cb_t` |
+------------------+-------------------------------------+
| Mesh ID | ID of ESP-MESH Network, |
| | see :cpp:type:`mesh_addr_t` |
+------------------+-------------------------------------+
| Router | Router Configuration, |
| | see :cpp:type:`mesh_router_t` |
+------------------+-------------------------------------+
| Mesh AP | Mesh AP Configuration, |
| | see :cpp:type:`mesh_ap_cfg_t` |
+------------------+-------------------------------------+
| Crypto Functions | Crypto Functions for Mesh IE, |
| | see :cpp:type:`mesh_crypto_funcs_t` |
+------------------+-------------------------------------+
The following code snippet demonstrates how to configure ESP-MESH.
.. code-block:: c
/* Enable the Mesh IE encryption by default */
mesh_cfg_t cfg = MESH_INIT_CONFIG_DEFAULT();
/* mesh ID */
memcpy((uint8_t *) &cfg.mesh_id, MESH_ID, 6);
/* mesh event callback */
cfg.event_cb = &mesh_event_handler;
/* channel (must match the router's channel) */
cfg.channel = CONFIG_MESH_CHANNEL;
/* router */
cfg.router.ssid_len = strlen(CONFIG_MESH_ROUTER_SSID);
memcpy((uint8_t *) &cfg.router.ssid, CONFIG_MESH_ROUTER_SSID, cfg.router.ssid_len);
memcpy((uint8_t *) &cfg.router.password, CONFIG_MESH_ROUTER_PASSWD,
strlen(CONFIG_MESH_ROUTER_PASSWD));
/* mesh softAP */
cfg.mesh_ap.max_connection = CONFIG_MESH_AP_CONNECTIONS;
memcpy((uint8_t *) &cfg.mesh_ap.password, CONFIG_MESH_AP_PASSWD,
strlen(CONFIG_MESH_AP_PASSWD));
ESP_ERROR_CHECK(esp_mesh_set_config(&cfg));
.. _mesh-start-mesh:
Start Mesh
^^^^^^^^^^
The following code snippet demonstrates how to start ESP-MESH.
.. code-block:: c
/* 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`.
.. --------------------- ESP-MESH Application Examples ------------------------
.. _mesh-application-examples:
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 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 ---------------------------
.. _mesh-api-reference:
API Reference
--------------
.. include:: /_build/inc/esp_mesh.inc