Industrialberry designed EthernetBerry Dual Pi V 1.1 an extension board for RaspBerry Pi.
It has two functionalities: a dual Ethernet interface and an on board Real Time clock powered by a 12 mm battery.
The Ethernet is based on ENC28J60 a SPI controller, it is a stand-alone Ethernet controller with an industry standard Serial Peripheral Interface (SPI).
The real time clock is based on DS3231 an I2C controller with internal oscillator.
The ENC28J60 meets all of the IEEE 802.3 specifications and it is full integrated in linux kernel.
For more technical details see: