Application example for 5160-BOB with encoder

normally encoder's A channel to A of TMC5160, channel B to B of TMC5160, N is the null or zero. 

if the direction reversed, A and B wire could be reversed or change the direction bit,

Thanks Koko, 

My encoder has an index, which I assume would be connected to the ENCN_DCO pin. 
However, I'm unclear on the power and ground connections for the encoder. 

I can, of course, connect power and ground to the 5V and GND lines of the pi, but I had expected there would be a 5V and GND reference on the 5160-BOB. 
Have you connected build this before and where did you connect the 5V and GND cables to?

yes, it is ok to use the internal 5V regulator output. 

solder a cable from this C4, use this as the power source of VDDIO and your encoder. 

thanks. or you can directly input a 5V input to VDDIO and your encoder.