Enhanced Serial Peripheral Interface (eSPI) Bus
Overview
The eSPI (enhanced serial peripheral interface) is a serial bus that is based on SPI. It also features a four-wire interface (receive, transmit, clock and target select) and three configurations: single IO, dual IO and quad IO.
The technical advancements include lower voltage signal levels (1.8V vs. 3.3V), lower pin count, and the frequency is twice as fast (66MHz vs. 33MHz) Because of its enhancements, the eSPI is used to replace the LPC (lower pin count) interface, SPI, SMBus and sideband signals.
See eSPI interface specification for additional details.