View Arduino Pro Mini Pinout I2C Background. The atmega328 also supports i2c (twi) and spi communication. The arduino software includes a wire library to simplify use of the i2c bus;

Reading I2c Sensor With Arduino Pro Mini
Reading I2c Sensor With Arduino Pro Mini from forum.arduino.cc
Notice in the pinout description that the analog pin number a4 and a5 has added functionality that is these pins together implement the i2c. Arduino promini , as the name indicates , is a miniature version of uno.it runs on 16 mhz crystal ,atmega328 ,but lacks usb connectivity. This board was developed for applications and installations where space is premium and projects are made as permanent set ups.

This board was developed for applications and installations where space is premium and projects are made as permanent set ups.

Arduino promini , as the name indicates , is a miniature version of uno.it runs on 16 mhz crystal ,atmega328 ,but lacks usb connectivity. Arduino promini , as the name indicates , is a miniature version of uno.it runs on 16 mhz crystal ,atmega328 ,but lacks usb connectivity. The arduino software includes a wire library to simplify use of the i2c bus; Arduino pro mini microcontroller development board is the variant of the arduino uno microcontroller board with specific perks and quirks.