interface

the interface consists in 3 sections, one for each audio channel/device.

each section consists in 2 columns. the right column of a section has an indicator for the position of the "beat", and its state (playing or not).

each column consists in 8 bytes.

a byte consists in 2 contiguous nibble dice: the one at the left is the high nibble, and the one at the right is the low nibble.

the bytes in a section map to the following aspects of the tracker and uxn audio device

first column

period ( 1 byte ) - how many frames have to happen to trigger a beat. if 0, the device is off
pattern ( 8 bits ) - each bit indicates if a note has to be played or not in that beat. bit 0 (least significant bit) corresponds to beat 0, bit 1 to beat 1, and so on.
beatcount ( 2 nibbles ) - definition of the beat count behavior. low nibble: how many beats happen in a cycle; if 0, there are no beats. high nibble: beat offset; starting value for the beat count. e.g. if high nibble is 2, and low nibble is 4, the beat count will repeat as 2, 3, 4, 5
adsr ( 2 bytes ) - envelope values, as described by the audio device reference
volume ( 2 nibbles ) - left and right volume values, as described by the audio device reference
sample ( 2 nibbles and 1 byte ) - definition of the sample to be used. high nibble: index of sample to use. low nibble + byte: length of the sample to use

available samples:

melody ( 8 bytes ) - midi notes corresponding to beats 0 to 7, from top to bottom.

you can find the code in the uxnería