Electronics for Building Things · Lesson 19 · Connectivity

Getting on Wi-Fi

The first step in making a gadget you can reach from anywhere in the house.

This track is the REPORT arrow from Lesson 18's SENSE → DECIDE → ACT → REPORT loop — and the reason you chose an ESP32 in the first place. It starts here: getting your board onto your home network so it can talk to your phone, a server, or Home Assistant.

The one win You understand how an ESP32 joins your Wi-Fi network and gets an address other devices can reach it at — and you know the gotchas that trip up every beginner.

Two Wi-Fi modes

Station mode (STA) — the ESP32 joins your existing home Wi-Fi, like your phone does. This is what you want for home automation.
Access Point mode (AP) — the ESP32 becomes its own little hotspot you connect to directly. Useful for initial setup (entering Wi-Fi details) or where there's no network.

(It can even do both at once, but start with station mode.)

What the code does

You don't need to memorize syntax, but recognize the shape — every Wi-Fi sketch follows it (Random Nerd Tutorials: ESP32 Wi-Fi functions):

Set station mode and call WiFi.begin(ssid, password) with your network name and password.
Wait in a short loop until WiFi.status() reports WL_CONNECTED — joining takes a moment.
Read WiFi.localIP() — the IP address your gadget was given.

The IP address: your gadget's house number

When the ESP32 joins, your router hands it an IP address (e.g. 192.168.1.42) — its address on your local network. Other devices in your house reach it at that number. (Next lesson, you'll type it into a browser to control the gadget.)

Tip Router-assigned IPs can change. For something you'll connect to often, set a static IP (or a DHCP reservation in your router), or give the board a hostname and reach it by name (more in Lesson 20).

The gotchas that waste hours

Read these now, thank yourself later

2.4 GHz only. The ESP32's Wi-Fi does not work on 5 GHz networks. If it won't connect, this is the #1 cause — use your 2.4 GHz SSID.
Don't hard-code credentials in shared code. Keep your Wi-Fi name/password in a separate secrets file you don't commit — especially with your repo public (like this course!).
Handle dropouts. Wi-Fi disconnects happen; add reconnection logic so your gadget recovers on its own.
Placement matters. Thick walls and distance weaken the signal; a flaky gadget is often just far from the router.

Check yourself

Read this next (primary source) Random Nerd Tutorials — Getting Started with the ESP32, then ESP32 Wi-Fi Functions for the connection code.

I'm your teacher — ask me anything. If your ESP32 won't connect, tell me what you see — nine times in ten it's the 2.4 GHz issue or a typo in the credentials, and I can help you spot it.