Tower of Power Design
While a few physical designs have been considered, this design is a backplane-like solution. Instead of a backplane, boards are stacked on top of each other and either stand up (like a tower) or lay horizontally. A rigid PCB backplane board is used to connect each of the cards.
Card Layout/Requirements
Stackup
It is recommended all cards be 4 layers with the following stackup:
| Layer | Purpose |
|---|---|
| Top | Bus Signals |
| Middle 1 | Ground |
| Middle 2 | +3.3V |
| Middle 3 | Local Signals, -/+ 12V |
For -/+ 12V use polygon pours and try to keep it away from signals if possible.
Different Board Types
This helps break up system functions in ways that can make prototyping easier.
Power
There could be multiple power board types for prototyping or to accept different power requirements for the user. There could be a standard half-wave rectified board that takes low voltage AC from a barrel jack, a full wave rectified that takes an AC plug and uses a transformer, a switching power, etc.
Mixer
This is a special board which only pulls power from the bus and provides audio headers to mix multiple boards together which have an audio solution (notably VERA and TurboWave).
Proposed Example Stack
Here is a proposed stack layout for what a user might want to build. Table is read from bottom up.
| Function | Device # | -------------- | | Audio Mixer | N/A | | Serial/Network | 6 | | MIDI | 5 | | TurboWave | 4 | | VERA | 3 | | MCU/Smart RAM | 2 | | ROAM | 0,1 | | CPU | N/A | | Power | N/A |
Note that in this proposed design, the Power board is always on the bottom.