The pepper analog outs are 0V : 5V and this is mapped to values 0 : 1 in PureData.
The base conversion is therefore:
analog = digital * 5V
where analog
is the analog voltage and digital
is the value inside Pd or C++.. I.e.:
Digital | Analog |
0 | 0V |
0.2 | 1V |
0.4 | 2V |
0.6 | 3V |
0.8 | 4V |
1.0 | 5V* |
* in practice 5V is hard to achieve because the power supply may saturate slightly below that.
Now, these values may not be mV accurate, so some calibration may be needed. That could be done by adding per-channel scaling and offset.
See here for a complete approach: https://forum.bela.io/d/3859-volt-per-octave-out-for-pepper