Today, i was thinking about how differents components will communcate and work together.  After some reading about i2c, serial, and other CAN possibilty, i was not convinced... this protocols are pretty old and i dont know them very well.  

I was a network engineer for 12 years ... So i decided to make them communicate with an internal Wifi network at 2.4Ghz. I will use RPi3 and many ESP32 to build the main core of the robot. Here's is how it work : 

• RPi3 will serve an acces point for remote control console,
• x Esp32 will connect to this internal Wifi secured by WAP2,
• Developpement and debug has to be done from an ethernet cable (SSH and xRDP accessing ubuntu desktop,).

I can now use as many ESP32 as i need and get "infinite" IO ports. Data from sensor will be published by an HTTP server with a json format, and some ajax call will display them in the remote HTTP console served by the RPi3.

I setted up a mDNS service, so i dont have to rember IP from esp32. just use come comon DNS name like : motors.local, or roboticarm.local ...

Here is a photo of my notes ... (sorry it's just a draft) : 

and what it look like in real life : 

have fun building robots, and thank you for following this little project.