My first impressions after seeing your Web site are that I’d love one of these - for my Raspberry P. Or my old Arduino. But - for the Beaglebone? Not so much.
The headers for the Pi and Arduino are stackable. At the moment, the headers for the Bone fail this test (judging by the 3D views - you may have changed these by now).
For the board itself… egad that’s a lot of adaptors. I’d be interested in how well it functions as a cross - adaptor, ie. Arduino Shields to Pi or Bone.
The board design has changed between the Pi and Bone 3D renders - but for both, it seems PMOD 6 (and I can’t even find PMOD 5) aren’t actually connected. I’d suggest you dump them.
As a test, stick an Arduino LCD shield (or similar) on top, and see if the the buttons are accessible, and LEDs visible. I suspect PB5 (Reset) and PB6 would have troubles. Same for the LEDs in a circle.
For analog in, you are relying on the microcontroller - that’s a limit of 200Ksps 10-bit. Better than nothing, but hardly ground-breaking.
TI has the ADS6244, Linear Technology has the LTC2144-14 (2 channel, 14-bit 105Msps) are two suggestions I’d make.
For outputs, you could be the heros of many people trying to use the Pi as a media centre: add a SPDIF coonection. Go optical, the TOTX173 (or similar) would be my choice.
Having screw terminals for the optional power in is great - but I don’t see any protection circuit for if the power is reversed. Just diodes to select the source to regulators U2, U4.
At the very least, I’d strongly recommend you add polarity indicators to the silkscreen mask. Hopefully you’ve already done this, and my observations (based on the 3D models) are obsolete.
When your design is out of beta stage, I’d suggest you get this guy to make a reference to it: Joel’s Cheap FPGA Development Boards
– Alan Campbell