This must be the easiest Papilio Project ever – use you FPGA board as a USB to 3.3V TTL RS232 adapter.

I’ve got a pcDuino and sometimes it is nice to have access to the serial console. Although you wouldn’t want to dedicate a board to it it is perfect for occasional use. As a bonus, due to the flexibility of the FPGA’s I/O pins you can use it for multiple different I/O standards and voltages – If you change to IOSTANDARDs and maybe the Vco jumper you have also got yourself 2.5V or 1.2V CMOS to USB adapter!

Original: http://hamsterworks.co.nz/mediawiki/index.php/USB_TTL_RS232