[sdiy] Micro as a Linear to Exponential converter?

[Colin f]

> and some  
> kind of interpolation too, if you want pitch bend or anything other  
> than exact MIDI notes.
> So, not "trivial", but not "difficult" either.

I've been looking at adding pitch-bend by switching around the DAC current
reference.
One mux channel would be used to generate a pitch-bent reference - the
original reference, which comes from the tune pot, multiplied by a
pitch-bend lookup table to give a range of 0.5 to 2.0 x the original
reference for maybe 10 bits of MIDI pitch range (depending on how big the
lookup gets).
That would be s/h-ed, then switched back into the DAC to act as the
reference for note CV channels.
That scheme would double the offset errors on the CV, but it only needs to
be switched in when pitch bend is active.
If the pitch bend was centred, you would just leave the original reference
switched in for the note CVs.

Cheers,
Colin f