Adding an Ethernet Port to your ESP32

Frank Sautter has an interesting post on his blog on adding a physical ethernet connector to an ESP32 development board.  The board he chose was the Waveshare LAN8720 and, apart from Frank Sautter's LAN8720 Adapter Boardone gotcha with GPIO0 during resets, it appears to be a fairly simple build.  The LAN8720 already has (some!) support from Espressif, so this seems like a nice, easy and relatively cheap way to build yourself a WiFi-to-Ethernet gateway.

Frank has detailed the connections for his adapter board and included a nice bottom view (left), so that it should be fairly easy to duplicate his build.  The LAN8720 boards themselves are currently available on eBay for about $3 each.



Olimex ESP32 Development Board

Just in case you haven’t seen it elsewhere already, the good news for ESP aficionados today is that Olimex have announced an ESP32-based (WROOM-32) development board with a couple of novel features.

Olimex ESP32 Dev Board

The most obvious is that prominent ethernet connector.  According to the specs it’s a “fast” ethernet port, so 10/100Mbs.  The two relays are rated at 10A/250V and it’s worth noting that, from the photograph of the bottom of the board, both the N/O (normally open) and N/C (normally closed) contacts are broken out to the screw terminals.

Olimex ESP32 Dev Board (bottom)

What makes that more useful than N/O only?  Well with two relays, you now have complete control over a switched device and the existing wall switch still works as normal if your ESP32 board is powered off:-

  • The N/C relay is in series with the existing wall switch and the N/O relay is in parallel.
  • If the light is switched on at the wall switch, you can switch it off remotely by activating the N/C relay to open the series contacts.
  • If the light is off at the wall switch, you can activate the N/O relay to close the parallel contacts, switching the light on.
  • Fail-safe operation. If the power to the ESP32 board fails, your wall switch still works as normal.
  • If the light isn’t being controlled by the ESP32 board, the relays are both off, so the relays don’t draw current and your wall switch, as above, still works normally.

This isn’t by any means novel, but a lot of the low-cost ESP relay control boards out there only have a single, normally-open relay contact pair available.

Moving on from the relays, there is also a micro-SD card slot available for on-board storage, two buttons, a decently sized barrel connector for an external +5V supply and a connector for a LiPo battery, with an on-board charger and step-up converter to enable battery powered operation.

There’s a 40-pin connector, which apparently gives access to all of the available GPIO pins (the pin map for the connector is silk-screened onto the bottom of the board) and, finally, a “UEXT” connector (the ten pin socket, next to the 40-pin connector).  If you’re not familiar with the UEXT connector (and I certainly wasn’t), it turns out that it’s something which Olimex developed, are already using on many of their boards and have made available to the community as an Open-Source (as in royalty-free) standard.  It consists of 3V3 and GND power pins, TX and RX serial pins, SDA and SCL I2C pins and MISO, MOSI, SCK and SSEL SPI pins.  Now before you get too excited and start pulling all of those 30-year-old floppy disk cables out of your junk box, you should note that there’s no special magic used here; the I2C and SPI busses are still basically short-haul, on-board interconnects and you won’t be connecting remote devices over miles of (ancient) ribbon cable.  On the other hand, it is quite a neat idea to be able to plug (for instance) an LCD display directly onto the board.  You can check Olimex’s UEXT documentation for a (surprisingly long) list of their boards which already have this connector built in.

Unfortunately, although they’ve announced the price, at €22, the board isn’t actually available for sale quite yet.  According to the Olimex blog, the prototypes are in and as soon as they’ve been tested and some example code has been written, it’ll be going into full production.

Thanks to CNXSoft for breaking the news on this one.

ESP32 Dev Boards @ CNX Software

CNX Software, a site definitely worth adding to your bookmarks, has just published a short list of ESP32 development boards, gleaned mainly from blogs and social media sites.  Some of them are work-in-progress and some of them appear to be vapourware, but it’s still an interesting article and a nice little teaser for those of us still searching for someone to throw a few dollars at for a real, live ESP32.

ESP32 Info

If you haven’t seen it already, I’d recommend you pop over to Hackaday and read through their latest “Hands On” article on the ESP32 …including the comments.  Both “igrr” (Ivan Grokhotkov, of ESP8266/Arduino fame) and “Sprite_tm” (Jeroen Domburg, of libesphttpd fame), who both actually work for Espressif nowadays, have joined in the conversation to answer the questions which the HaD crowd have and straighten out any misconceptions.  It’s turning into one of the longest, most interesting and on-topic threads that we’ve seen for quite a while.

The floodgates open …and then close again, rather quickly

Hot on the heels of the development board “presents” from Espressif, one of our other noted suppliers, Seeed Studio, has started selling their ESP3212 (“Wifi Bluetooth Combo Module”), which bears only the slightest similarity to the

ESP32 Module
via Seeed Studio

WROOM-32 picture which was aired a couple of weeks ago (it’s a castellated module with an ESP32 and Flash on-board, other than that, even the pin counts are different).  The Seeed module has the AI-Thinker logo on the RF shield, so it looks as though this is the real-world module which should be readily available from your favourite Middle Kingdom sellers any time now.

Which is just as well.  Seeed Studio sold out of their initial inventory somewhat quicker than instantly and the next batch aren’t expected to arrive until October.  Having said that, it’s definitely worthwhile taking a look at their page to see the specs laid out in a nice, uncluttered and understandable way.

ESP32 Module, Top
via Seeed Studio

…and the lucky winners are

Seems like Friday was a big day in various parts of the world, with the postman delivering presents to several lucky recipients.  The contents?  A nice, shiny, new ESP32 development board.

ESP32 dev board with touch switches
Courtesy of Alasdair Allan

So far, people in India, Germany and the U.K. have reported receiving their early chrissy presents (the photo above was tweeted by Alasdair Allan, in the U.K.).  I would guess that there are now a few other people nailing wood across the front of the kennel to make sure the dog doesn’t chase the postie on Monday morning.

On a slightly more serious note, take a look at the header pins on the extreme left-hand side of the photo.  Now do a size comparison with the connections on the module itself; to me they look about half the size of the pads on the ESP8266 modules.  If that’s the case, then we can forget about soldering these little beasties by hand.  😦