Arduino- Pixhawk pins

Hi everyone!!

I am working on a collision avoidance system on quadcopters. However I am confused how to connect the Arduino to the Pixhawk. For example which pin should be connected where

Can anyone help?

Thanks a lot!!

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Pixhawk is a controller for things like quadcopters or UAVs.
https://store.3drobotics.com/products/3dr-pixhawk?taxon_id=34

You will probably get a better answer at diydrones.com