OK. There are 3 different versions of Nano:

Nanosynth
http://gbdev.gg8.se/files/musictools/Ol … Nanosynth/

Nanovoice
http://gbdev.gg8.se/files/musictools/Ol … Nanovoice/

and Older? First? version of Nanosynth (called Nanovoice) (with source code in C)
http://swiki.hfbk-hamburg.de/MusicTechnology/132

Nanosynth can't be synced via some clock (serial port of Gameboy) ...

Nanovoice can be synced in the same way as Old Nanoloop, as E.S.C. mentioned...

About First version of Nanosynth/Nanovoice (from one of my old posts):
The only difference against the other Nanosynth rom is, that when you hit Start, it doesn't switch between mono / stereo delay mod, but it switches between normal / sync mod
in Sync mod it waits for triggering:
I remember that connecting 2 of GB serial's pins triggers a note, disconnecting these pins triggers another note etc...
You can try it alone, or I can try it same as you from a scratch
There was (maybee!) some other thing to do, connect one of another pins to ground. I actually don't remember that. It's more than year I tried to work with this rom.
...

not sure which version you're using, but some versions of nanovoice take external sync signals (same as the nanoloop 1.0-1.3 carts/roms) http://gbdev.gg8.se/files/musictools/Ol … Nanovoice/

I will try to figure out the tempo of each. I did it once before, but my notebook is gone. I ran it as slave.

I love the sounds of nanosynth/nanovoice and want to run it alongside lsdj or anything else.
I was wondering if anyone has tracked the bpm of the different tempo settings within the program, or has any advice on getting as smooth of a sync as possible