Marcel Kilgus, better known for his software projects with QPC and SMSQ/E, has turned hardware tinkerer with this project to allow a USB mouse to be used with a SuperQBoard interface.
Marcel found the “New MKIV Amiga/Atari USB mouse adapter” for about 16€ plus postage. Atari mice are generally the type used for the QL, too, so Marcel just went ahead and bought it.
The first tests a few days later weren’t that encouraging, nothing worked at all. So he had a look at the schematics of the SuperQBoard and found out that although electronically it’s Atari/QIMI compatible, it used a completely different pin layout.
Have a look at his article on his blog at https://www.kilgus.net/2017/01/30/of-mice-and-men-but-mostly-mice/ for details of how he rewired the mouse to work with this interface.