I also recommend USB Made Simple [1], which has similar vibe to this site, but also includes USB 2.0 description and is a bit more detailed on electrical/low le

I also recommend USB Made Simple [1], which has similar vibe to this site, but also includes USB 2.0 description and is a bit more detailed on electrical/low level aspects. For an actual implementation, see V-USB [2] - surprisingly readable software library for bit-banging USB on AVR (Arduino/ATTiny/ATMega) [1] https://www.usbmadesimple.co.uk/index.html https://www.usbmadesimple.co.uk/index.html [2] https://github.com/obdev/v-usb https://github.com/obdev/v-usb