Shields

The only ENC28J60 Ethernet shield suitable for 3.3 V and 5 V Arduino currently (2024) on the market is the HW-270 shield by Shenzhen Yihexin Electronic Technology Co., Ltd.

Almost all other Arduino ENC28J60 shields for Uno use a schematic based on the schematics recommended in the ENC28J60 datasheet for a 5 V MCU and they use logic gates (74HCT08) instead of a Tri-State Digital Buffer (74HC125) to convert the MISO line to 5 V. This creates problems. SPI device not selected by CS pin should release the MISO line by setting the output pin to HI-Z state. The enc28j60 of course does this, but the logic gate can't. It stays HIGH, blocking the bus. No other device can be used on SPI with this shield attached. (Many 5 V SD card adapters have the same problem with then level conversion on the MISO line.) The problem can be solved by removing the 74HCT08 IC and adding a solder bridge for MISO line continuity.

The 3.3 V Arduino boards (Zero, Due, Giga, Adafruit Metro with a 3.3 V MCU) could be damaged by ENC28J60 shields with 5 V logic level conversion, while without the 5 V conversion the ENC28J60 is OK with a 3.3 V Arduino. The shields can be modified to work with a 3.3 V Arduino by removing the 74HCT08 and fixing the 5 V pull-up resistors used on some shields. The shield will still work with a 5 V Arduino.

On the picture the 74HCT08 is removed and the solder bridge in yellow circle is for MISO, the bridge in the blue circle is for the INT line.

Some shields may require a modification of the pull-up resistors to 3.3 V: