Why invent yet another protocol ?
The MIDI protocol was invented in the early 80s to interconnect musical instruments together and, a bit later, to computers. While MIDI is quite outdated now, it has no real substitute.
Nowadays most of computer peripherals, control interfaces, and DIY microcontroller boards are connected to the computer by the USB. Unfortunately USB doesn't fix most of the MIDI limitations (except for data rate), length of the cables is even more limited ; configuration process is also harder and delicate when you have multiple devices.
Of course Ethernet would be the way, but this is not the same class, for both cost and hardware/software complexity.
RS485 needs quite a simple hardware setup, while being able to long distance at sufficient rates. It just requires an UART for the microcontroller to communicate.
But RS485 is only a physical layer, not a protocol… There stands Fraise.
Fraise was invented after we explored, while building Metalu's creations, both DMX512 protocol (since 2005, for controlling light and speed of hacked Super8 film projectors) and a ad-hoc bidirectional computer/multiple-boards protocol, which was named Fraise1.0 when developed in 2007, while building a musical set of buried step sensors.
Fraise1.0 was convincing about exchanging data between multiple microcontroller boards and the computer, but it didn't tolerate long cables very well.
Although DMX512 has proven its robustness in long distance experiments, it isn't suited for bidirectional communication.
We finally choose to mix both solutions, and developed Fraise2.0 (in 2010) that implements a duplex communication on RS485 physical layer (which uses 2 wires to allow balanced signal transmission).
Then we improved the protocol a bit, introducing current 2.1 version in 2013, which adds checksum error control and special low-level protocol for bootloader communication purpose, to allow reprogramming the boards through the same bus.