Excerpt from the README.md:
This is a project that attempts to make all (or at least most) of the I/O on the ESP8266 available over the network. Currently this includes GPIO's (as GPIO or PWM), I2C and the UART.
The GPIOs can be selected to work as "normal" input, "normal" output, "bounce" mode (this means trigger once, either manually or at startup, or "blink" continuously) or "pwm" mode (16 bits PWM mode, running at 330 Hz, suitable for driving lighting).
The "normal" UART lines (TXD/RXD) are available and are bridged to the ESP8266's ip address at port 25. This is unless the UART lines are re-assigned as GPIOs, which is also possible.
GPIOs can also be selected to work as i2c lines (sda, scl). You can use the "raw" i2c send and receive commands to send/receive arbitrary commands/data to arbitrary slaves. For a number of i2c sensors there is built-in support, which allows you to read them out directly, where a temperature etc. is given as result.
The firmware also listens at tcp port 24, and that is where the configuration and commands go to. Type `telnet <ip_address> 24` and type `?` for help.
The project is still in development, expect more features in the future.
The source can be found at github, here: http://github.com/eriksl/esp8266-universal-io-bridge, please read the README.md for more information.
The original topic can be found here: viewtopic.php?f=11&t=3212