ESP32 WiFi in the simulator

ESP32 boards in Velxio come with working WiFi. The emulated radio scans, associates, gets an IP address over DHCP and reaches the internet through the emulator’s NAT gateway. It is the real WiFi stack from the vendor SDK running on an emulated radio, not a stub: the same sketch, unchanged, runs on the physical chip.

This page goes from a first connection to your own networks, packet captures and your real LAN.

Your first connection

1. Open the gallery example Connect to WiFi (/example/esp32-wifi-connect), or drop any ESP32 board on the canvas and paste the sketch below.
2. Press Run. The first compile of a session takes longer; later ones are cached.
3. Open the Serial monitor from the toolbar under the canvas.
4. Watch the join: the SDK’s own boot chatter, then the DHCP lease.

#include <WiFi.h>

const char* WIFI_SSID = "Velxio-GUEST";  // built-in, open network

void setup() {
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID);

  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
    Serial.print(".");
  }

  Serial.printf("\nConnected. IP: %s\n", WiFi.localIP().toString().c_str());
  Serial.printf("Gateway:      %s\n", WiFi.gatewayIP().toString().c_str());
  Serial.printf("RSSI:         %d dBm\n", WiFi.RSSI());
}

void loop() {}

The serial monitor shows the join and the address the emulated DHCP server handed out:

One thing surprises everybody the first time: the log says Connecting to Espressif even though the sketch names Velxio-GUEST. That is the SSID rewrite doing its job, and the next section explains it.

The IP is real inside the simulation: sockets, HTTP clients and MQTT libraries work from here on. See MQTT and HTTP for complete projects.

The built-in networks

Without any access-point part on the canvas, the radio beacons four demo networks. A station associates with exactly one of them:

SSID	Channel	Signal	Auth
Velxio-GUEST	6	-20 dBm	Open
PICSimLabWifi	1	-25 dBm	WPA2-PSK
Espressif	5	-30 dBm	WPA2-PSK
MasseyWifi	10	-40 dBm	WPA2-PSK

The SSID in your sketch does not matter

While the project has no access point part, the network name you write is not the one the board joins. On its way to the emulator the compiler rewrites every SSID literal to Espressif and blanks every password literal, whether it is a variable, an array, a #define or a struct field:

const char* ssid = "MyHomeNetwork";   // compiled as "Espressif"
#define WIFI_PASS "hunter2"           // compiled as ""

That is why a sketch copied from any tutorial connects here without being edited, why passing a wrong password never fails, and why the serial log names a network you did not type. Nothing is wrong when that happens.

Two consequences worth knowing:

• Adding an access point part switches the rewrite off. From then on the project defines its own airspace, so what you type is what exists and the SSID has to match a part.
• Firmware that arrives already built never passes through the rewrite. It hunts for the SSID baked into the binary, which is why an otherwise working .bin can sit there failing to associate. Either rebuild it naming one of the four networks above, or broadcast the SSID it expects with an access point part.

MicroPython

import network
import time

WIFI_SSID = "Velxio-GUEST"

sta = network.WLAN(network.STA_IF)
sta.active(True)
sta.connect(WIFI_SSID)

while not sta.isconnected():
    time.sleep(0.25)

print("Connected. ifconfig:", sta.ifconfig())

sta.scan() returns the same networks the Arduino API sees, as (ssid, bssid, channel, rssi, authmode, hidden) tuples.

Your own networks

With a Maker plan you are not limited to the demo networks. A WiFi Access Point part makes the emulated radio broadcast your SSID.

1. Click Add Component on the canvas toolbar.
2. Search for WiFi Access Point and place it. It needs no wiring: it has no pins, it is airspace.
3. Select the part and set ssid to the network you want, for example HomeNet.
4. Point the sketch at that name and press Run.

WiFi.begin("HomeNet");   // the SSID on your Access Point part

As soon as a project contains one access point part, the built-in networks go silent. A scan then sees exactly what the canvas defines, which is what makes network-selection code testable.

Part properties

Property	Default	What it does
ssid	MyNetwork	The network name your sketch connects to.
password	empty	Stored and shown on the card. The network still broadcasts open auth until WPA2 lands, so sketches that pass a password connect anyway.
channel	6	WiFi channel, 1 to 13. Reported by scans.
rssi	-50	Signal strength in dBm as the board sees it, -90 to -20. Repeated scans jitter a few dB the way real ones do.
internet	on	Off makes the network isolated: the board associates and gets an IP, but nothing routes out.
bssid	empty	AP MAC address. Empty means a stable one generated from the SSID.

Try it in one click: Connect to your own WiFi network (/example/esp32-custom-wifi-ap) opens with the part already placed. Running it scans, finds exactly your network, and joins it:

Several networks at once

Add one part per network to exercise a picker or a “strongest first” policy. Each carries its own channel and signal, so a scan comes back ordered the way a real one would:

int n = WiFi.scanNetworks();
for (int i = 0; i < n; i++) {
  Serial.printf("%2d: %-16s ch %2d  %d dBm\n",
                i + 1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i));
}

Scan several WiFi networks (/example/esp32-wifi-scan-multi) ships three parts: HomeNet at -40 dBm, Office_5G at -62 dBm and CoffeeShop at -78 dBm.

Captive portals and provisioning

Turn internet off on a part and the network becomes isolated. The board associates and gets a DHCP lease, but no traffic leaves. That is the provisioning scenario: the device comes up, finds no way out, and serves its own configuration page.

Captive portal on an isolated network (/example/esp32-wifi-captive-portal) sets this up with an AP named SetupAP.

The WiFi panel

A WiFi badge appears on the canvas toolbar when you press Run, and leaves on Stop: it belongs to the running simulation, so there is nothing to open before starting one. It is gray while the stack boots and green once the board has an address.

The badge is a split button. The icon keeps its one-click action: with an IP, it opens the board’s web server through the IoT gateway. The caret next to it opens the WiFi panel:

The panel shows:

• Networks on the air, with channel and signal. The heading says this project when access point parts define them, and built-in when the four demo networks are on air:

  

• the board’s association state and its IP once DHCP completes;

• Download PCAP, the run’s 802.11 traffic as a capture file;

• the local network gateway section. On a Maker plan it holds the pairing field; on the free plan it explains what the gateway does and links to the plans.

Capture the traffic and open it in Wireshark

1. Press Run and let the sketch do its network work.
2. Open the WiFi panel and click Download PCAP.
3. Open the file in Wireshark.

The capture holds management frames, DHCP, DNS and TCP, with simulated-time stamps, so dhcp or dns as a display filter isolates the handshake you are debugging. The file is produced in your browser: nothing is uploaded.

Reaching your own machine

The networks above route to the public internet. To reach the MQTT broker, Home Assistant or dev server running on your machine, run the local gateway: see Local network gateway. Sketches then reach your machine as host.velxio.internal.

Ready-made examples

Example	What it shows
Connect to WiFi	The minimal join to a built-in network
Scan WiFi networks	scanNetworks() against the built-in set
Connect to your own WiFi network	One access point part, scan and join
Scan several WiFi networks	Three networks with different channels and signal
Captive portal on an isolated network	internet off, provisioning flow
NTP clock over your WiFi	UDP out to a real time server
Fetch JSON from a web API	HTTPClient against a real REST API
Reach a service on your own network	host.velxio.internal through the local gateway
MQTT	Publish and subscribe on a public broker

Troubleshooting

Symptom	Cause	Fix
Uploaded firmware never associates	Its SSID is baked in, so the compiler could not rewrite it	Name a built-in network, or add an access point part with that SSID
A scan returns only your networks	Working as intended: one access point part silences the built-in set	Remove the parts to get the demo networks back
Associates and gets an IP, but nothing routes out	The part has internet turned off	Turn it on, unless you are testing a captive portal
A password does not get rejected	WPA2 emulation is not in yet, the network broadcasts open auth	Expected for now; the password is stored on the part
host.velxio.internal does not resolve	No local gateway paired	See Local network gateway

Which boards

WiFi is available across the simulated ESP32 family: the classic ESP32 boards, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-C5, plus their XIAO, Nano and M5Stack variants. The Raspberry Pi Pico W has its own CYW43 emulation. Bluetooth advertising state is also reported for sketches that initialize BLE.