Arduino i2c - Testing an Automatic Control System

2 Arduino connected through i2c
Slave Arduino reads data from phototransistor and send them to Arduino Master
This change PWM command so that the engine has run 4 rotations per second as set.

I2C - Arduino connect to Arduino

I was able to connect two Arduino via i2c :D

my homemade tachometer.

I tested my homemade tachometer for Arduino.