A uHAT for the Raspberry Pi (Zero), which adds a second USB 2.0 controller over SPI, using the MAX3421E chip.
Also read my blog post for this project: https://chrz.de/2023/12/05/fido2-hardware-part-2-usb-host-circuit-boards/
KiCAD version 7 is used to edit the files. Inspired by the Mini USB Host Shield 2.0 (https://laborjag.com/venta/arduino/mini-usb-host-shield-2-0/).
See § "Compiling the MAX3421-HCD Kernel Driver" and § "Automatic Driver Loading and Device Tree Configuration" of my blog post at https://chrz.de/2023/11/07/fido2-protocol-translation-hardware/