At Antmicro we work with a large variety of FPGA chips, starting from very large FPGAs we’re using for prototyping ASIC systems, to super small, resource constrained devices to be deployed at the very edge.
One of such devices is the tiny and open source Fomu, containing a Lattice iCE40 FPGA chip with a set of peripherals such as pads meant for touch input and SPI Flash for storage, fitting inside a USB port. Thanks to its small size, hackability, availability of DFU bootloader, good documentation, Renode and Verilator simulation support and ability to work as any USB device, Fomu is a perfect platform for developing projects using USB, such as pen test tools.
In this blog note we will present the details of one of our latest projects called Fomu keystroke injector, which reimplements the functionality of the USB Rubber Ducky pen test tool using only the Fomu FPGA board.