Hi Gary,
Already got you covered on this one. The original problem was the inputs were scaled to
only approx. 10 volts. The internal A/Ds are ratiometric to the 5 volt supply, that can vary
by 10%, then each channel is only matched to 1% because of the resistors.
The new input structure will have a trimmable input where the A/D reading can be
adjusted to exactly 1023 for an exact 5.000 volt input for each of the 4 channels. That will
read a 5 octave keyboard. Hopefully that is enough keyboard range.
The input routine may have to be 60 conditional statements to convert the voltage into
semitone note values. Perhaps an equation that reads the real input voltage, subtracts
0.044 volts and divides the result by 0.0833 volts and round off to get a semitone number
between 0 and 59.
Only thing is to try it and see what works reliably.
> I want to bring up an issue that was uncovered in early PSIM usage -
> although the DAC outputs were precise enough for 1 v/oct scaling, the
> INPUTS were not as precise - for instance, when using Woody Wall's
> Quantized Shift Register, errors were discovered when sampling a
> pre-quantized source (the shift register's output was a different
> pitch than the input). When discussing this with Grant, he surmised
> that it was the lack of bit resolution on the input side, which had a
> limited precision - therefore the encoding error. Can we address this
> hardware issue?
>
> Conxiser this please, oh kind sirs, (bowing as I recceed back into the
> shaddows) 8-)
>
> gary
>