Hey,
I've been trying to squeeze a decent arpeggio out of mgb via the nanoloop usb midi adapter using pitch bend messages and failed miserably, because the pitch bend steps are so low res that I can't even hit half-tones properly and everything is just ever so slightly detuned against each other.
Take a listen: http://wolkenspeicherplatz.de/sound/gb_test_2.mp3
This is the closest I was able to get near each note I wanted to hit in the arps.
After checking some things I found out that mgb apparently only interprets 5 bits of the high res signal, resulting in a total of 32 steps, when other hardware interprets at least 7 bits (ignoring the low byte) or even 14 bits (with the low byte interpreted). To make things worse, the frequency changes in a non-linear fashion, with exceedingly higher steps towards the top end.
Can anyone confirm that a real arduinoboy also produces only 32 frequency steps over the entire pitch bend range? Just want to rule out that the usb midi adapter is at fault for what ever reason.