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Teensy-Only Wiznet Ethernet Library

This copy of Ethernet for Wiznet chips is intended only for Teensy boards. For using with any non-Teensy board, please use Arduino's Ethernet:

Or use the copy of Ethernet from your board's vendor, if they publish a modified copy of Ethernet specifically for their boards.

A bit of history

Back in 2018, I worked on unifying support for all 3 Wiznet chips (available at that time) with many performance improvements I had developed for Teensy's copy of Ethernet. I tested on many boards and it was released as Arduino Ethernet version 2.0.0.

For a brief time, I was officially the maintainer for Arduino's Ethernet library. However, months later Arduino changed their repository access requirements, which I could not meet. I also became very busy with developing Teensy 4.0, leaving little time for testing Ethernet on other hardware.

In 2020, we released Teensy 4.1 with native ethernet, which offers vastly better performance than using a Wiznet chip. I do not anticipate spending much development time on Wiznet support in the foreseeable future. If you use Ethernet with Teensy, please consider Teensy 4.1 for future projects. The performance is so much better.

If you use a non-Teensy board, this is not the Ethernet library for you. Please do not report issue or ask for technical support for non-Teensy boards on this Teensy-specific repository.

Improved Performance Ethernet Library

Wiznet chips W5100, W5200 and W5500 are automatically detected.

Efficient block mode of W5200 & W5500 are used for data and multi-byte register access.

Wiznet socket registers are cached, which greatly reduces SPI communication overhead, at the cost of a small increase in RAM usage. TCP connections and UDP packets accessed in small chunks typically see a substantial performance boost.

Adafruit's Ethernet.init(CSPIN) extension is supported, to allow use of different pins for the chip select signal. Optimized direct register I/O is used for most Arduino compatible boards.

Tested Hardware

Board Chip Shield / Module Internet Local (LAN)
Teensy 3.6 W5500 WIZ850io 212.59 1143.58
Teensy 3.6 W5200 WIZ820io 202.44 1102.71
Teensy 3.6 W5100 WIZ812MJ 180.76 274.14
ESP32 Feather W5500 Featherwing Ethernet 211.06 965.76
Teensy 3.2 W5500 WIZ850io 205.37 958.06
Teensy 3.2 W5200 WIZ820io 215.44 914.78
Teensy 3.2 W5100 WIZ812MJ 170.07 234.55
ChipKit Uno32 W5500 Seeed Ethernet W5500 177.19 858.81
ChipKit Uno32 W5200 WIZ820io 188.31 837.56
ChipKit Uno32 W5100 Ethernet R2 (clone) 159.72 272.18
Arduino Due W5500 Seeed Ethernet 214.44 689.69
Arduino Due W5200 WIZ820io 206.51 670.88
Arduino Due W5100 Arduino Ethernet R3 105.98 109.73
ESP8266 Feather W5500 Featherwing Ethernet fail (dns) 583.31
Teensy LC W5500 WIZ850io 200.51 479.73
Teensy LC W5200 WIZ820io 199.62 471.95
Teensy LC W5100 WIZ812MJ 126.40 137.77
Arduino 101 (Intel) W5500 Seeed Ethernet W5500 168.96 359.32
Arduino 101 (Intel) W5200 WIZ820io 169.37 349.35
Arduino 101 (Intel) W5100 Arduino Ethernet R3 42.39 43.60
Teensy 2.0 W5100 WIZ812MJ 81.07 84.85
Arduino Uno R3 W5500 Seeed Ethernet W5500 185.44 329.00
Arduino Uno R3 W5500 Ethernet2 195.32 329.60
Arduino Uno R3 W5200 WIZ820io 191.85 331.27
Arduino Uno R3 W5100 Arduino Ethernet R3 79.11 82.66
Arduino Uno R3 W5100 Ethernet R2 (clone) 79.27 82.66
Arduino Leonardo W5500 Seeed Ethernet W5500 179.98 328.14
Arduino Leonardo W5200 WIZ820io 183.69 330.30
Arduino Leonardo W5100 Ethernet R2 (clone) 78.75 82.28
Mega 2560 (clone) W5500 Seeed Ethernet W5500 179.58 323.36
Mega 2560 (clone) W5200 WIZ820io 172.73 325.44
Mega 2560 (clone) W5100 Ethernet R2 (clone) 74.31 77.44
Arduino Zero W5500 Seeed Ethernet W5500 183.13 305.26
Arduino Zero W5500 Ethernet2 181.60 305.28
Arduino Zero W5200 WIZ820io 177.53 298.53
Arduino Zero W5100 Arduino Ethernet R3 91.33 96.64
Arduino Zero W5100 Ethernet R2 (clone) 91.42 96.64
Arduino MKR1000 W5500 MKR ETH 181.27 298.93
Arduino MKR1000 W5200 WIZ820io 125.20 291.98
Arduino Uno Wifi Rev2 W5500 Seeed Ethernet W5500 163.86 213.36
Arduino Uno Wifi Rev2 W5500 Ethernet2 169.72 212.88
Arduino Uno Wifi Rev2 W5200 WIZ820io 161.94 212.19
Arduino Uno Wifi Rev2 W5100 Ethernet2 69.50 72.23
Arduino Uno Wifi Rev2 W5100 Ethernet R2 (clone) 69.55 72.30

For more information about these benchmarks:

ESP32 may require edit to SPI.h to add SPI.transfer(data, size)