dreams: Midi2cv redux

The building blocks:

1. Mutable Instruments CVPal
2. 1:5 MIDI Thru

The mods:

1. Modify the CVPal firmware to accomodate Serial MIDI instead of USB midi. This allows it to work with my existing Alesis MIDI keyboard.
2. Modify the CVPal Firmware to accept MIDI Program Change events. This replaces the Channel-based behavior of the stock firmware.
3. Modify the CVPal Firmware to use a hardware channel setting / indication. Either dedicated buttons and displays, or a documented key combination and indication on the GATE output.
4. Modify the 1:5 MIDI thru to include 3x of the CVPal and 1x MIDI Thru output
5. The unused slot on the MIDI Thru bus can be occupied by a custom microcontroller to facilitate the newly supported MIDI Program Changes. This could further be expanded to support a MIDI file player or other MIDI controls.

I guess i need to go parts shopping because i don't have any of hex inverters in this schematic. I also need some 20Mhz xtals for the ATTiny84 in the CVPal.