This is shorthand for the protocol used originally by Teletype for remote control of other Monome Eurorack modules over an I2C bus (jumper cables between pin headers on the rear of the modules). Communication over this bus is now supported by a number of different modules by different manufacturers: Mannequins Just Friends and W/, the dedicated TELEX expanders, O|D ER-301, the 16n faderbank, SSSR Labs Matrixarchate, and now Crow. Other eurorack players have hinted (?) possible I2C features, including Intellijel and ALM. In Crow’s case, transmitting arbitrary I2C messages to arbitrary addresses has been made generic and reprogrammable on the fly in Lua, making it easier than ever to expand the possibilities of the “ii” bus.
In my experience and @scanner_darkly’s , multi-leader setups with the existing libavr32 stack (TT/ansible/trilogy/aleph(?)) are usable, but unstable. In spite of some patches @scanner_darkly made to gracefully retry / give up on failed I2C operations instead of blocking indefinitely, I still experience crashes when sending a lot of traffic to TXo from both Ansible and Teletype (which is a ton of fun until that happens!). There is a lot still to figure out here and with the release of Crow I am sure some evolution of the protocol to work for more complex networks of devices will be very interesting.
Needless to say I have bought one of these and am thrilled about working with this ecosystem further.
More info: 1, 2.
