Minimalist Network-on-Chip
For background, see https://www.youtube.com/watch?v=bjUphH1a1vc
Using Ethernet to interconnect a Raspberry Pi cluster seems a bit clunky.
Instead, we build a minimalist Network-on-Chip on an ICE40 FPGA, using SPI to interface with the Pi nodes.
We can use SPInet with the Raspberry Pi Zero, which has no built-in Ethernet, to make an extremely compact cluster. Here an Altera Cyclone II FPGA is used for the Network-on-Chip circuit.
Finally the SPInet circuit is implemented on an ASIC (sub-design 6 below) as part of a multi-project chip using the Caravel framework from efabless.com
