The WiFi name, password and the station location (geohash) are not written in the code. They live in the board's flash memory and are entered through setup mode: the AirBox opens its own WiFi hotspot with a small configuration page. You can change them any time without reflashing.
The ESP32 only speaks 2.4 GHz WiFi. A network that is 5 GHz only will never be found, no matter how correct the password is. Networks that need a login page (hotel or school portals) do not work either, the station has no browser to log in with.
Press the setup button and keep it held for 15 seconds. This works from any state, even while the station is sleeping: the button wakes it up.
You know you are in setup mode when the LED stays solid on.
A freshly flashed board has no WiFi settings at all, so it boots straight into setup mode by itself. In that case skip the button and go to step 2.
If you release the button too early the station just continues whatever it was doing. Try again and count the full 15 seconds.
On your phone or laptop, join this network:
AirBox-Setupairbox-setupYour phone will likely warn that this network has no internet. That is normal, stay connected anyway.
On most phones the page pops up on its own a few seconds after connecting (the same way hotel login pages do). If nothing appears, open a browser and go to:
http://192.168.4.1
The page has three fields:
Press Save & reboot. The station stores the values and restarts in normal mode.
If you only wanted to look and change nothing, press Leave setup mode instead: the station reboots and keeps its old settings.
Be patient here. The station does not connect immediately after the reboot: it first checks the temperature probe, then preheats the air sensor for 5 minutes, and only then connects and uploads. So the first data appears on the dashboard about 6 to 7 minutes after the reboot, and then roughly every 16 minutes.
If you have a USB cable and the serial monitor open (115200 baud), you can watch it happen live: a connected line with an IP address, then a POST line and HTTP 200 (accepted).
http://192.168.4.1 in the browser by hand, and make sure your phone did not silently jump back to its usual WiFi (some phones leave networks that have no internet).Setup mode can be entered as many times as you like, nothing breaks by trying.