smartHub

The smartHub is a dispatch module for the I²C bus, with one input connection to the RoboTX I²C master and four output connections for I²C slaves.

It is encased in a 9V red battery box (references 32263 and 32958). 

The 9V red battery box makes it perfect to be included in a fischertechnik model.

I²C Bus Repeater

The smartHub features an I²C bus repeater to ensure good quality of I²C signals.

Long cables increase capacitance, making the bus more prone to data error. A repeater allows the I²C bus to be extended, without degradation of performance even during level shifting.

I tested different solutions from NXP and TI intensively. I discarded most of the repeaters as they weren't compatible with the RoboTX or failed to protect the I²C bus from interferences.

The smartHub doesn't require any command to work.

Finalised and Working Hub

The smartHub was built directly, thanks to prior tests with I²C repeaters and hubs.

In the model pictured, the I²C cables sum more than 1 metre long in a dense and heavily polluted environment, due to the proximity of many motors and solenoids. 

The I²C slave devices are (clockwise, from top left) : 

• dual stepper controller (red box, top left), 
  
• smartRFID sensor (yellow box, top right), 
  
• smartColours sensor (red box, bottom right) 
  
• and RGB LED (white box, bottom left).
  

No data loss was reported.