esp8266_ethernet

Example of using SPI Ethernet module with esp8266.
Arduino core for ESP8266 uses lwip for TCP/IP protocol stack.
The hierarchy of programs that use WiFi is as follows:

+----------------+
|  Application   |
+----------------+
| Network Object |
+----------------+
|      lwip      |
+----------------+
|   WiFi Driver  |
+----------------+

The latest Arduino core supports SPI external Ethernet as standard.
You don't need any libraries.
The hierarchy of programs that use Ethernet is as follows:

+----------------+
|  Application   |
+----------------+
| Network Object |
+----------------+
|      lwip      |
+----------------+
| Ethernet Driver|
+----------------+

Hardware requiment

SPI Ethernet module using this chip.

ENC28J60
W5100
W5500

Software requiment

Arduino core for ESP8266 V3.0.2 or later

You can check the Core version using ESP.getFullVersion() or ESP.getCoreVersion().
This is mine:

ESP.getFullVersion=SDK:2.2.2-dev(38a443e)/Core:3.0.2=30002000/lwIP:STABLE-2_1_2_RELEASE/glue:1.2-48-g7421258/BearSSL:6105635
ESP.getCoreVersion=3.0.2

Wireing

SPI PHY	---	ESP8266
SCK	---	GPIO14
MISO	---	GPIO12
MOSI	---	GPIO13
CS	---	GPIO16(*)
RST	---	RESET

(*) You can change.

Selecting the Ethernet module

Using W5500:

#include <W5500lwIP.h>
Wiznet5500lwIP eth(CSPIN);

Using W5100:

#include <W5100lwIP.h>
Wiznet5100lwIP eth(CSPIN);

Using ENC28J60:

#include <ENC28J60lwIP.h>
ENC28J60lwIP eth(CSPIN);

Limitations