Maybe I should use the same structure as the monome 40h or series protocol.
http://docs.monome.org/doku.php?id=tech:protocol:40h
http://docs.monome.org/doku.php?id=tech:protocol:serial:series
I already implemented the series serial protocol on another project, and I didn't have any problem at 115200bps.
It takes 2 bytes per row (16 bytes for the whole screen) and works well.