Motorcontroller and arduino

[SailingRiver]

You should not use 5v, you must use 3v3 or can damage the pi

Hopefully the serial wiring explains well enough:
https://pypilot.org/schematics/hbridge_datasheet.htm

Hi thanks for you reply but i already viewed that. My question is how do I connect the arduino nano to the motor controller you provided or should I directly link the motorcontroller to the pi? And is i can directly link the motorcontroller to the pi how should i do that? 

I have tried connecting the controller using the pin you give in the diagram enabling uart connecting and assigning uart using pypilot directly and also using serial, but it doesn't recognize anything in pypilot. 

I read almost all forms and i thought you wrote once that connecting to the motor controller using the arduino would be better. I dont know i am kind of at a loss i have been working on this project for a long time now....