You need a nightly version greater than esp32-20171031 (31 Oct. 2017)! Versions older than this one have a problem with the DNS address of the access point (see here). A tutorial to install MicroPython on the ESP32 can be found here.

Install the captive-portal dependencies (picoweb, micropython-logging, utemplate, micropython-pkg_resources, micropython-btreedb). I included the file `setup_sta_upip.py`. You need to change the `your_ssid`, and the `wpa2_password` to the corresponding of your network and execute the file on the PyMark console (click on the run button).

The configuration variables are located in this file. The logged data will be save on a file on the WeMos. To do that, you can choose between 3 possibilities (btree, filedb or sqlite). I tested only btree ;). This can be selected using the variable `DB_BACKEND`. The variable `DB_PASSWORD` is the admin password. I included an admin section to read the database. The user is admin, the password is defined using `DB_PASSWORD`. The DNS service only responds to the requests that contain at least of the words from the array `DNS_ANSWERS`. This reduces the CPU workload. The words listed per default are the required in order to get the "connect to a network" message (you should not remove any of them). You can add others to this array. The problems with sockets that I described in the Wemos-Alexa blog article has also consequences here. The number of opened sockets is limited. You can expect some fatal error from the picoweb service.

The `homepage.html` is the web page that the users see after clicking on the "connect to a network" message. You can include some JavaScript files, images and CSS style files in the static folder too. The WiFi speed is slow. The portal should be not to big (I included one sample portal, but it should be a lighter one - optimization is required here!). If you are an advanced user, you can also modified the `admin.html` and `login.html` pages. These two files are only for you to see the logged data (administrator section).