I have been following this thread for some time. I currently connect to my AVX via that hand controller but going forward I would like to connect my Raspberry Pi directly to my mount via the AUX port and to start using this driver.
However I am struggling to undestand how to do this. Is there a pre-built USB -- RJ12 cable that can be purchased from somewhere?
Or can I use a USB FTDI TTL 5V cable and connecting the correct pins to the RJ12 plug and make it work? 
I'd like to do the second option but as far as I can tell from reading numerous sources on the web, this cannot be done.

 

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