NOTE [Nov 2020] — It seems as though the “June 2019” fix (immediately below this paragraph) is no longer required. I downloaded the project directly from the GitHub repository and compiled with the latest version of PlatformIO (5.0.2) a few days ago and it compiled, uploaded and worked with no changes at all, so I’d suggest you try it and only use the following fix if you see the “invalid abstract” errors.
Update June 2019 — A couple of people have mentioned (both here and on GitHub) that they are having difficulty compiling the code for this project, with “invalid abstract return type” errors. This turns out to be an upstream problem caused by a non-backward compatible modification of the Espressif arduino/ESP32 library. You can force the build to use an older (compatible) version of the library by changing a single line in your platformio.ini file:-
— platform = espressif32
++ platform = firstname.lastname@example.org
Thanks to @maniekQ for documenting this workaround.
Over the past couple of days, in the course of answering questions on the popular article on adding an ethernet port to the ESP8266, I found myself putting up a link to some new code for a work-in-progress project which simply replaces the ESP8266 with an ESP32 (which seems to make a lot of sense, given the falling cost of the ESP32 modules, nowadays). While that project is for an ESP-Now gateway, it seemed like there was a need for a nice, simple test and verify project where people can do a minimum of work with the hardware (an ESP32, a W5500 module, some jumper leads and a breadboard) and get a working result in a reasonably short time. I’d said in various places that it shouldn’t take too much work to modify the code for the ESP-Now project to handle any of the examples shipped by default with the Arduino Ethernet library, so that’s what I’ve done.
Here’s the code (along with the pinouts in the README) for the simple “UdpNtpClient” example, munged very slightly to work with the ESP32. All it does is connect to an NTP server, retrieve the current timestamp and display the UTC time. This is basically a 30-minute project to produce a working demostration of an ESP32 using hard-wired Ethernet.
The configuration uses a static IP and network setup (router/gateway, netmask and DNS), as the original ESP8266 project seemed to have problems with DHCP (and quite honestly, I just haven’t gotten around to trying it with the ESP32 version, yet …let me know how it goes if you do). All of the configuration options are in the “local_config.h” file.
The original library example code uses a single NTP server, “time.nist.gov”, which seemed a little anti-social to me, so I’ve added several of the more popular geographical pools into the config file and updated the default target to be the main “pool.ntp.org”. You should choose the one closest to you (unless you’d like to see how unreliable bare UDP really is, in which case you might like to try “antarctica.pool.ntp.org” — apologies if you’re reading this from McMurdo Station 🙂 ).