Particle Gen 3 devices including the Argon, Boron, and B Series SoM have the ability to use Ethernet.
For the Feather form-factor devices (Argon, Boron) this is typically done using the Ethernet FeatherWing.
Note that the Wiznet W5500 does not support Auto MDI-X so you may need a crossover cable when connecting directly to a computer or laptop instead of an Ethernet switch.
Ethernet must be enabled. This is done using
System.enableFeature(FEATURE_ETHERNET_DETECTION);from code, or from the mobile app. The reason is that probing for the Ethernet controller will use SPI and the GPIO pins above, which would adversely affect code that does not use Ethernet but does use those pins for other purposes.
FEATURE_ETHERNET_DETECTIONflag only needs to be enabled once. It's stored in configuration flash and will survive reset, power down, user firmware flashing, and Device OS upgrades.
Device OS has limited fallback support for switching between network layers, described in detail below.
Ethernet requires a DHCP server on the network. It cannot be used with a static IP address.
There is no support for Ethernet on Gen 2 devices (Photon, P1, Electron, E Series). There is not enough room for it on the Photon and P1, and the Electron/E Series TCP/IP stack is completely different and incompatible and difficult to port to, and there is not enough space for it.
Device OS only uses the presence of Ethernet link and the ability to obtain a DHCP address for the availability of Ethernet. If Ethernet is available, it will always be used instead of the device's other network (Wi-Fi for Argon or cellular for the Boron or B Series SoM).
This has two consequences:
It is not possible to use Ethernet to communicate with devices on an isolated LAN, then backhaul the data over cellular. One common use-case of this is Modbus TCP to sensors on Ethernet.
If the Ethernet LAN is normally connected to the Internet, it's not possible to fall back to cellular if this Internet connection goes down. This is possible to implement using a 3rd-party library in your application, see the ethernet reference guide for more information.