The MidiSportNxN (N=1,2,4,8) manufactured by MidiMan is a serie of USB to MIDI adaptors. MidiMan includes driver for Windows and Mac with their product but they expressed not to make drivers for Linux available in any future nor to technical information without NDA. Since MidiMan's firmware and policy is neither compatible with the USB-MIDI specification nor with Freeware standards, it became necessary to write this piece of code.
The MidiSport1x1 hardware uses the EZUSB chip (AN2131SC), which is base on Intel's 8051 and especially adds a USB core. The chip contains all the hardware necessary for an adaptor or micro controler, i.e. timers, serial and parallel ports together with 8 kByte of RAM. MidiMan added the glue logic, and the plugs.
The firmware is not burned into a ROM, but instead downloaded over the USB wire.
Since both USB-MIDI class drivers and EZUSB firmware loading drivers were available at the time, the project started, making the MidiSport1x1 going reduced to writing a firmware for the EZUSB chip. This was further simplified by a large stack of public available documentations on the chip (both from Intel and Cytrex) and by a rich freeware infrastructure around it, most notably the SDCC compiler, which allowed to write the whole firmware in C.
The author holds both the MidiSport hardware and the firmware for only one example of a large class of adaptors and controlers and hopes that the software included might help with other projects, too.