icehat is a small (Zero-sized) RPi hat which comprises a Lattice iCE40 Ultra FPGA type ice5LP4K-SG48 along with voltage regulators, status LEDs and three Digilent-style PMOD connectors.
This repository includes the full KiCAD board design source as well as C source for an RPi user application which can configure the FPGA via GPIO and SPI ports as well as communicate with a simple SPI slave hosted on the FPGA. Verilog source for the FPGA test design is also included.
For more info on this project, please see the web page at:
http://ebrombaugh.studionebula.com/embedded/icehat/index.html
Credits:
Portions of the KiCAD design are based on the RPi_Hat_Template from xesscorp: https://github.com/xesscorp/RPi_Hat_Template