System76 EC is a GPLv3 licensed embedded controller firmware for System76 laptops. It is designed to be portable to boards using several 8-bit microcontrollers, such as:

Board	Embedded Controller	Architecture
System76 ecsim	Simulated ITE EC	8051
System76 Laptops	ITE IT8587E	8051
System76 Thelio Io	Atmel ATMEGA32U4	AVR
Arduino Mega 2560	Atmel ATMEGA2560	AVR

Shared features (that can be used across different micro-controllers):

Acronym	Feature	Description
ADC	Analog-digital converter	Reads voltages from batteries and temperature from thermistors
DAC	Digital-analog converter	Brightness control of keyboard backlight
GPIO	General purpose input/output	Control of LED's, buttons, and enable lines for other hardware
KBSC	Keyboard scan controller	Detects laptop keyboard presses. Keyboard scanning can be done using GPIOs, the ITE EC has hardware acceleration
PS/2	Keyboard and mouse bus	Interfaces with touchpad. PS/2 can be done using GPIOs, the ITE EC has hardware acceleration
PWM	Pulse-width modulation	Fan control and brightness control of LED's
SMBUS	System management bus	Reads battery information
SPI	Serial peripheral interface	Reads and programs the EC's firmware
UART	Universal asynchronous receiver-transmitter	Provides EC console input/output

Features specific to ITE embedded controllers:

Acronym	Feature	Description
LPC	Low pin count	Forwards memory and I/O access to EC. Most EC functions are exposed to the host through this interface. High frequency makes a GPIO implementation not possible. Simulation is provided by System76 ecsim
PECI	Platform environment control interface	Reads CPU temperature (relative to throttle point). Proprietary nature means a GPIO implementation is unlikely, though not technically impossible

Features specific to Atmel embedded controllers:

Acronym	Feature	Description
USB	Universal serial bus	Can be used to provide access to EC functions either to the host or to a remote machine