ESP32 & ESP8266 Connectivity · Intermediate · Discovery
ESP32 mDNS Service Discovery
Reach the board by name instead of an address that changes every time the router feels like it.
Firmware status: Generated from this project's own pin map and compiled with arduino-cli for esp32:esp32:esp32 before publication; bench validation on your hardware is still required.
Board: ESP32 DevKit (ESP32-WROOM-32, 30 or 38 pin) · ESP32 dual core @ 240 MHz · 3.3 V logic · build for esp32:esp32:esp32.
What you will build
An ESP32 publishing an mDNS hostname and HTTP service, so the build is reachable at a stable name.
Components
- ESP32 board
- USB cable
- A phone or computer on the same network
Pin map for this build
| Sketch constant | Pin | What it is |
|---|---|---|
PIN_OUT_1 | 4 | Switched output — relay / MOSFET channel, 5 V coil |
PIN_IN_1 | 34 | Analog input — 3.3 V maximum at the pin |
Tools
- USB programming cable
- Multimeter
- Current-limited bench supply (for anything that switches a load)
- Small screwdriver and wire cutters
Build sequence
- Flash and note the printed hostname.
- Open the hostname from a phone on the same network.
- Reboot the router and confirm the address changes but the name still resolves.
- If the name does not resolve, check the client operating system before changing the sketch.
Test and expected result
The name resolves on the local network, survives a router reboot, and the page loads from a phone.
Acceptance checks
name resolves, page loads by name, survives address change
Safety and limits
mDNS is local-network only and unauthenticated. It is a convenience for your own bench, not a public address.
Hardware scope
mDNS responder, HTTP service advertisement, hostname registration.
Connection diagram
Download the connection diagram (SVG)
Download the Arduino sketch (E20_esp32_mdns_service_discovery.ino)
Guide source: the sketch on this page was generated from the pin map above and compiled for esp32:esp32:esp32 before publication.
Related projects
- ESP32 Captive Portal Wi-Fi Manager — Boot the ESP32 with no credentials and configure its network from a phone, with the portal saved to flash.
- ESP8266 Config Portal — The same idea on the cheapest board that can do it: an ESP8266 that configures itself from a browser.
- ESP8266 Sensor Portal Logger — A battery-minded sensor node you configure in the field, with the reading shown on its own setup page.