I’ve received the boards for the iCE40 add-on back from DirtyPCBs, and they look good. As far as I can tell, everything seems to be functional, although I’ve got some coding to do before I can tell for certain – in particular, I need to put together a bootloader of some sort to feed the SPI port on the iCE40 with the bitstream.
In the meantime, I’ve put together one of these boards and got it powered up in a spare novena to test, and I’ve quickly thrown together enough Verilog code for the Xilinx to be able to bit-bang SPI to talk to the iCE40.
For anyone following along, the only mistake I’ve noticed on these boards has been the wrong footprint for the upper pass-through connector; the one I’ve used is close enough to fit, but there’s some definite overhang on the pins over the pads, and it’d be wise to redo that part if you’re considering making one of these boards. I’d also recommend using the taller version of the lower connector, as I found the board sits slightly high at one side as a result of resting on the SATA connector. It’s flat enough to still make good contact, however, so if you only have the shorter connectors, you should be OK.
Here’s the board sitting in place in the novena (with a patch wire onto the reset pin during bringup):
and with the GPBB fitted on top:-
Also about this board: