Lattice iCE40 is documented [1] and it has fully open source development tools [2], [3]<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;cliffordwolf&#x2F;icestorm" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;cliffordwolf&#x2F;icestorm</a><p>[2] <a href="http:&#x2F;&#x2F;www.clifford.at&#x2F;yosys&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.clifford.at&#x2F;yosys&#x2F;</a><p>[3] <a href="https:&#x2F;&#x2F;github.com&#x2F;cseed&#x2F;arachne-pnr" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;cseed&#x2F;arachne-pnr</a>