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Wi-Fi API

About

The Wi-Fi API provides support for the 802.11b/g/n protocol driver. This API includes:

  • Station mode (STA mode or Wi-Fi client mode). ESP32 connects to an access point
  • AP mode (aka Soft-AP mode or Access Point mode). Devices connect to the ESP32
  • Security modes (WPA2, WPA3 etc.)
  • Scanning for access points

Working as AP

In this mode, the ESP32 is configured as an Access Point (AP) and it's capable of receiving incoming connections from other devices (stations) by providing a Wi-Fi network.

../../_static/wifi_esp32_ap.png

This mode can be used for serving an HTTP or HTTPS server inside the ESP32, for example.

Working as STA

The STA mode is used to connect the ESP32 to a Wi-Fi network, provided by an Access Point.

../../_static/wifi_esp32_sta.png

This is the mode to be used if you want to connect your project to the Internet.

API Description

Here is the description of the WiFi API.

Common API

Here are the common APIs that are used for both modes, AP and STA.

onEvent (and removeEvent)

Registers a caller-supplied function to be called when WiFi events occur. Several forms are available.

Function pointer callback taking the event ID:

typedef void (*WiFiEventCb)(arduino_event_id_t);
wifi_event_id_t onEvent(WiFiEventCb, arduino_event_id_t = ARDUINO_EVENT_MAX);

Function pointer callback taking an event-ID-and-info struct:

typedef struct{
    arduino_event_id_t event_id;
    arduino_event_info_t event_info;
} arduino_event_t;

typedef void (*WiFiEventSysCb)(arduino_event_t *);
wifi_event_id_t onEvent(WiFiEventSysCb, arduino_event_id_t = ARDUINO_EVENT_MAX);

Callback using std::function taking event ID and info separately:

typedef std::function<void(arduino_event_id_t, arduino_event_info_t)> WiFiEventFuncCb;
wifi_event_id_t onEvent(WiFiEventFuncCb, arduino_event_id_t = ARDUINO_EVENT_MAX);

A similar set of functions are available to remove callbacks:

void removeEvent(WiFiEventCb, arduino_event_id_t = ARDUINO_EVENT_MAX);
void removeEvent(WiFiEventSysCb, arduino_event_id_t = ARDUINO_EVENT_MAX);
void removeEvent(wifi_event_id_t = ARDUINO_EVENT_MAX);

In all cases, the subscribing function accepts an optional event type to invoke the callback only for that specific event; with the default ARDUINO_EVENT_MAX, the callback will be invoked for all WiFi events.

Any callback function is given the event type in a parameter. Some of the possible callback function formats also take an arduino_event_info_t (or use arduino_event_t which includes both ID and info) which is a union of structs with additional information about different event types.

See WiFiGeneric.h for the list of event types and "info" substructures, and also see a full example of event handling: events example.

Warning

Event callback functions are invoked on a separate thread (FreeRTOS task) independent of the main application thread that runs setup() and loop(). Callback functions must therefore be thread-safe; they must not access shared/global variables directly without locking, and must only call similarly thread-safe functions.

Some core operations like Serial.print() are thread-safe but many functions are not. Notably, WiFi.onEvent() and WiFi.removeEvent() are not thread-safe and should never be invoked from a callback thread.

setHostname (and getHostname)

Sets the name the DHCP client uses to identify itself. In a typical network setup this will be the name that shows up in the Wi-Fi router's device list. The hostname must be no longer than 32 characters.

setHostname(const char *hostname);

If the hostname is never specified, a default one will be assigned based on the chip type and MAC address. The current hostname (default or custom) may be retrieved:

const char *getHostname();

Warning

The setHostname() function must be called BEFORE WiFi is started with WiFi.begin(), WiFi.softAP(), WiFi.mode(), or WiFi.run(). To change the name, reset WiFi with WiFi.mode(WIFI_MODE_NULL), then proceed with WiFi.setHostname(...) and restart WiFi from scratch.

useStaticBuffers

This function is used to set the memory allocation mode for the Wi-Fi buffers.

static void useStaticBuffers(bool bufferMode);
  • Set true to use the Wi-Fi buffers memory allocation as static.
  • Set false to set the buffers memory allocation to dynamic.

The use of dynamic allocation is recommended to save memory and reduce resources usage. However, the dynamic performs slightly slower than the static allocation. Use static allocation if you want to have more performance and if your application is multi-tasking.

By default, the memory allocation will be set to dynamic if this function is not being used.

setDualAntennaConfig

Configures the Dual antenna functionallity. This function should be used only on the ESP32-WROOM-DA module or any other ESP32 with RF switch.

bool setDualAntennaConfig(uint8_t gpio_ant1, uint8_t gpio_ant2, wifi_rx_ant_t rx_mode, wifi_tx_ant_t tx_mode);
  • gpio_ant1 Configure the GPIO number for the antenna 1 connected to the RF switch (default GPIO2 on ESP32-WROOM-DA)
  • gpio_ant2 Configure the GPIO number for the antenna 2 connected to the RF switch (default GPIO25 on ESP32-WROOM-DA)
  • rx_mode Set the RX antenna mode. See wifi_rx_ant_t for the options.
  • tx_mode Set the TX antenna mode. See wifi_tx_ant_t for the options.

Return true if the configuration was successful.

For the rx_mode you can use the following configuration:

  • WIFI_RX_ANT0 Selects the antenna 1 for all RX activity.
  • WIFI_RX_ANT1 Selects the antenna 2 for all RX activity.
  • WIFI_RX_ANT_AUTO Selects the antenna for RX automatically.

For the tx_mode you can use the following configuration:

  • WIFI_TX_ANT0 Selects the antenna 1 for all TX activity.
  • WIFI_TX_ANT1 Selects the antenna 2 for all TX activity.
  • WIFI_TX_ANT_AUTO Selects the antenna for TX automatically.

WiFiAP

The WiFiAP is used to configure and manage the Wi-Fi as an Access Point. This is where you can find the related functions for the AP.

Basic Usage

To start the Wi-Fi as an Access Point.

WiFi.softAP(ssid, password);

Please see the full WiFiAP example in: ap example.

AP Configuration

softAP

Use the function softAP to configure the Wi-Fi AP characteristics:

bool softAP(const char* ssid, const char* passphrase = NULL, int channel = 1, int ssid_hidden = 0, int max_connection = 4, bool ftm_responder = false);

Where:

  • ssid sets the Wi-Fi network SSID.
  • passphrase sets the Wi-Fi network password. If the network is open, set as NULL.
  • channel configures the Wi-Fi channel.
  • ssid_hidden sets the network as hidden.
  • max_connection sets the maximum number of simultaneous connections. The default is 4.
  • ftm_responder sets the Wi-Fi FTM responder feature. Only for ESP32-S2 and ESP32-C3 SoC!

Return true if the configuration was successful.

softAPConfig

Function used to configure the IP as static (fixed) as well as the gateway and subnet.

bool softAPConfig(IPAddress local_ip, IPAddress gateway, IPAddress subnet);

Where:

  • local_ip sets the local IP address.
  • gateway sets the gateway IP.
  • subnet sets the subnet mask.

The function will return true if the configuration is successful.

AP Connection

softAPdisconnect

Function used to force the AP disconnection.

bool softAPdisconnect(bool wifioff = false);

Where:

  • wifioff sets the Wi-Fi off if true.

The function will return true if the configuration is successful.

softAPgetStationNum

This function returns the number of clients connected to the AP.

uint8_t softAPgetStationNum();

softAPIP

Function to get the AP IPv4 address.

IPAddress softAPIP();

The function will return the AP IP address in IPAddress format.

softAPBroadcastIP

Function to get the AP IPv4 broadcast address.

IPAddress softAPBroadcastIP();

The function will return the AP broadcast address in IPAddress format.

softAPNetworkID

Get the softAP network ID.

IPAddress softAPNetworkID();

The function will return the AP network address in IPAddress format.

softAPSubnetCIDR

Get the softAP subnet CIDR.

uint8_t softAPSubnetCIDR();

softAPSubnetMask

Get the softAP subnet mask.

IPAddress softAPSubnetMask();

softAPenableIPv6

Function used to enable the IPv6 support.

bool softAPenableIPv6(bool enable=true);

The function will return true if the configuration is successful.

softAPIPv6

Function to get the IPv6 address.

IPAddress softAPlinkLocalIPv6();

The function will return the AP IPv6 address in IPAddress format.

softAPgetHostname

Function to get the AP hostname.

const char * softAPgetHostname();

softAPsetHostname

Function to set the AP hostname.

bool softAPsetHostname(const char * hostname);

Where:

  • hostname sets the device hostname.

The function will return true if the configuration is successful.

softAPmacAddress

Function to define the AP MAC address.

uint8_t* softAPmacAddress(uint8_t* mac);

Where:

  • mac sets the new MAC address.

Function to get the AP MAC address.

String softAPmacAddress(void);

softAPSSID

Function to get the AP SSID.

String softAPSSID(void) const;

Returns the AP SSID.

WiFiSTA

The WiFiSTA is used to configure and manage the Wi-Fi as Station. The related functions for the STA are here.

Basic Usage

The following code shows the basic usage of the WifiSTA functionality.

WiFi.begin(ssid, password);

Where the ssid and password are from the network you want to connect the ESP32.

To check if the connection is successful, you can use:

while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
}

After a successful connection, you can print the IP address given by the network.

Serial.println("IP address: ");
Serial.println(WiFi.localIP());

Please see the full example of the WiFiSTA in: sta example.

STA Configuration

begin

  • Functions begin are used to configure and start the Wi-Fi.
wl_status_t begin(const char* ssid, const char *passphrase = NULL, int32_t channel = 0, const uint8_t* bssid = NULL, bool connect = true);

Where:

  • ssid sets the AP SSID.
  • passphrase sets the AP password. Set as NULL for open networks.
  • channel sets the Wi-Fi channel.
  • uint8_t* bssid sets the AP BSSID.
  • connect sets true to connect to the configured network automatically.
wl_status_t begin(char* ssid, char *passphrase = NULL, int32_t channel = 0, const uint8_t* bssid = NULL, bool connect = true);

Where:

  • ssid sets the AP SSID.
  • passphrase sets the AP password. Set as NULL for open networks.
  • channel sets the Wi-Fi channel.
  • bssid sets the AP BSSID.
  • connect sets true to connect to the configured network automatically.

Function to start the connection after being configured.

wl_status_t begin();

config

Function config is used to configure Wi-Fi. After configuring, you can call function begin to start the Wi-Fi process.

bool config(IPAddress local_ip, IPAddress gateway, IPAddress subnet, IPAddress dns1 = (uint32_t)0x00000000, IPAddress dns2 = (uint32_t)0x00000000);

Where:

  • local_ip sets the local IP.
  • gateway sets the gateway IP.
  • subnet sets the subnet mask.
  • dns1 sets the DNS.
  • dns2 sets the DNS alternative option.

The function will return true if the configuration is successful.

The IPAddress format is defined by 4 bytes as described here:

IPAddress(uint8_t first_octet, uint8_t second_octet, uint8_t third_octet, uint8_t fourth_octet);

Example:

IPAddress local_ip(192, 168, 10, 20);

See the WiFiClientStaticIP.ino for more details on how to use this feature.

STA Connection

reconnect

Function used to reconnect the Wi-Fi connection.

bool reconnect();

disconnect

Function to force disconnection.

bool disconnect(bool wifioff = false, bool eraseap = false);

Where:

  • wifioff use true to turn the Wi-Fi radio off.
  • eraseap use true to erase the AP configuration from the NVS memory.

The function will return true if the configuration is successful.

isConnected

Function used to get the connection state.

bool isConnected();

Return the connection state.

setAutoConnect

Function is deprecated.

getAutoConnect

Function is deprecated.

setAutoReconnect

Function used to set the automatic reconnection if the connection is lost.

bool setAutoReconnect(bool autoReconnect);

Where:

  • autoConnect is set to true to enable this option.

getAutoReconnect

Function used to get the automatic reconnection if the connection is lost.

bool getAutoReconnect();

The function will return true if this setting is enabled.

setMinSecurity

Function used to set the minimum security for AP to be considered connectable.

bool setMinSecurity(wifi_auth_mode_t minSecurity);

Where:

  • minSecurity is the minimum security for AP to be considered connectable. Default is WIFI_AUTH_WPA2_PSK.

WiFiMulti

The WiFiMulti allows you to add more than one option for the AP connection while running as a station.

To add the AP, use the following function. You can add multiple AP's and this library will handle the connection.

bool addAP(const char* ssid, const char *passphrase = NULL);

After adding the AP's, run by the following function.

uint8_t run(uint32_t connectTimeout=5000);

To see how to use the WiFiMulti, take a look at the WiFiMulti.ino example available.

WiFiScan

To perform the Wi-Fi scan for networks, you can use the following functions:

Start scan WiFi networks available.

int16_t scanNetworks(bool async = false, bool show_hidden = false, bool passive = false, uint32_t max_ms_per_chan = 300, uint8_t channel = 0);

Called to get the scan state in Async mode.

int16_t scanComplete();

Delete last scan result from RAM.

void scanDelete();

Loads all infos from a scanned wifi in to the ptr parameters.

bool getNetworkInfo(uint8_t networkItem, String &ssid, uint8_t &encryptionType, int32_t &RSSI, uint8_t* &BSSID, int32_t &channel);

To see how to use the WiFiScan, take a look at the WiFiScan.ino or WiFiScanAsync.ino example available.

Examples

Complete list of WiFi examples.

Wi-Fi AP Example

.. literalinclude:: ../../../libraries/WiFi/examples/WiFiAccessPoint/WiFiAccessPoint.ino
    :language: arduino

Wi-Fi STA Example

.. literalinclude:: ../../../libraries/WiFi/examples/WiFiClient/WiFiClient.ino
    :language: arduino

Wi-Fi Events Example

.. literalinclude:: ../../../libraries/WiFi/examples/WiFiClientEvents/WiFiClientEvents.ino
    :language: arduino