[beagleboard] Couple questions

All the pins not listed as being for eMMC and HDMI are free to use. Of course, you can use them as well, assuming you can modify your code to support that.

Yes, the boot pins are also shared by the HDMI pins. This is all described in the System Reference Manual. http://circuitco.com/support/index.php?title=BeagleBoneBlack#Hardware_Files

There is this link on the card that came in the box. If you still have it, go to the link and you will find some useful information. BOMS, schematics, System Reference Manuals, etc.

If not, here is the link http://circuitco.com/support/BeagleBoneBlack


make sure your opto can deal with 3.3v . most need a bit more to function

i was unable to quickly find a datasheet on that part to check