I mean no offense to your opinions, but I've had a heck of a lot more fun designing the Compac than I would have had working on an FPGA board. I like to work with hardware instead of pretending to work with hardware, and programming a thing to think it's the hardware I want is not nearly as fun as getting iron burns.
Fun, and a perception of play, is a very individual thing. The only 'fun' that I can recall that involved soldering irons was when the professors left the room, we over-applied the rosin-based flux and played really loud "Smoke on the water" by Deep Purple on the tape recorder and tried to come up with alternative lyrics to that song. I'll be perfectly happy to never need to touch the soldering iron again in my life and do all my work by supplying design plans to the workshops.
Integrating a microcontroller with digital voltage control and temp sensing will go on the next model up.
I'm glad to hear that you are considering next version.
But you are going to commit a grave mistake if its going to have a programmable microcontroller with firmware. USB 2.0 has enough bandwidth to support all the required circuitry in the completely dumb-terminal mode.
Unfortunately I don't know the specifics of the ASIC you are using, but the general design points are as follows:
1) absolutely no firmware or microcontrollers can be run on the same power supply as the mining chip !!!one!eleven!
2) simple, high bandwidth USB to serial converter chip with high noise immunity using SPI, I2C, plain serial with hardware flow control, etc.
3) pre-calibrated SPI/I2C thermometer IC touching the same heathsink
4) external clock generator with programmable frequency and duty cycle.
5) SPI/I2C interfaced programmable voltage converter
6) if the chip doesn't have a an on-die temp-sensing diode maybe there is a way to rig up a temperature sensor by doing e.g. IO-pad leakage to time converter with external RC components and measure chip temperature indirectly by measuring time in the host software.
7) obviously, if there is an on-die diode then just hook it up the external thermometer IC.
Don't dis the manual voltage adjustment
I'm trying to. But I sense that you are probably not aware what can a single person do with e.g. a copy of National Instruments LabView Student Edition when that person doesn't need to practice screwdriver artistry and work around firmware limitations/bugs/faults but can simply do a proper laboratory workflow by setting up operational points (voltage,clock parameters) and measure the outputs (temperature,hashing speed & error rates).
One additional comment about the lame design choice that Spondoolies made: they used on-chip temperature-to-digital converter macro instead of a cheaper and simpler diode with external thermometer IC. The internal SSN (simultaneous switching noise) on their chip made their temperature readouts rather unreliable. And they knew very well that the SHA256 mining chip is very close to the theoretical maximum toggle rate of any practical digital circuit.
