Well, I've gotten to the design point where real money starts to be involved. I'm going to need licenses from the HDCP folk, along with any other audio formats the device will handle. That just leads into having some initial mock-ups built. That'll also cost money.
How much money is the question. HDCP membership is going to be around $1500 a year. I figure another $5000 will cover the consulting, and fabrication of the first prototype device.
Found Noritake Itron who makes VFDs (Vacuum Florescent Displays). Not only will they build custom displays, and mount them on PCBs with all the needed drive components, they can also incorporate push buttons for the user interface. I may be able to get them to build the full UI board.
Have the basic ideas for the power supplies complete. There will be a 115/230 volt, 50/60 Hz transformer which will output around 9 volts AC. Both the main board, and DAC board will have their own power supply sections. Rectifying and regulating the power to the needed levels.
Most of the main board, and all of the DAC board will be behind relays. The DAC board being dual regulated, with a series regulator, for most of it, and then shunt mode regs for the 3.3 volt reference signals. The shunt regs draw power all the time, especially when the devices behind them are shut down. So there needs to be a way to cut them off from the transformer completely. Thus the relay. The main board will also have a relay cutting down on draw when the system is asleep. Only enough power to run the UI board, and it's IR receiver will be in use. The UI board will be able to close the relay on the main board to wake it up, and then the main board closes the DAC relay when it comes time to initialize it.
All power supply sections will be linear rather than switched mode. That'll cut down on the electrical noise considerable (both internally, and also fed back out onto the power line). Linear supplies are not as efficient as switched mode, so this processor probably won't qualify for Energy Star status, but that's fine. One doesn't buy a super car for fuel economy; if I may be allowed an automotive analogy.
Looking at power supply designs, based upon the requirements of the various boards. The DAC board needs various voltage levels, and an inverted polarity for some parts. The main board is a little more simple in it's needs, plus no need for extremely accurate reference voltages as are required when entering the analog world.
I think I can get everything done with a single transformer with an output somewhere between 7 to 9 volts. I'm used to the requirements of power amplifiers, looking at logic level electronics everything is to a much smaller scale. That makes things both easier and harder.
Wow, high quality clocks, like Crystek's CCHD-950 are really expensive. Sticking 16 of them on a board will add over $400 to the price. That's no good. So I'll have to find a clock distribution circuit which can send the clock signal to each DAC without adding much noise or jitter.
Things are slowing down a little bit. Mostly because the first batch of research work is done, and now the actual designing has to happen. It's easy enough to look up a part, or read some datasheets in my down time, but I need dedicated hours to do any serious designing. So I'll be limited to mostly weekends.
Otherwise, the Sil Image sheets are great. Though their chips have so many interconnects, that I'm probably going to have to locate them on the main board rather than on a sub-board. One less board might actually make things cheaper.
Silicon Image really came through. After receiving my NDA they delivered no just two datasheets, but nine huge PDFs. I've got some reading to do.
