Over on Hackaday.io, [Dave Vandenbout] has posted the CAT board, a Raspberry Pi
daughterboard hat that features a Lattice FPGA, 32 MB of RAM, EEPROM, and a few Grove and PMOD connectors. The CAT takes advantage of the open source tool chain available for Lattice including the Python-based MyHDL (although, you could just use Verilog directly, if you prefer) and Icestorm. One interesting point: you can run the tool chain on the Raspberry Pi, resulting in a self-contained and largely portable FPGA development environment.
The design files are actually on Github. You may notice the SATA connectors. However, [Dave] doesn’t know if you could really use SATA drives with them–they are there for general purpose differential I/O.
It is great to have an open source board and tool chain for FPGA development. We’ve talked about the open source Icestorm toolchain before and MyHDL, too. If you prefer, most of the vendor FPGA tools are free to use for many common devices and uses. The Lattice tools should work just as well with this board, even if it does offend your open source sensibilities.
The video below introduces the CAT board, but be warned: it does contain actual cat pictures. It does not, however, contain any apologies to Dr. Seuss.