This code runs in a Raspberry Pi Zero, and controlls an 18 bells pneumatic bell tower, using two IO Pi Zero boards and then a driver module composed of triacs.
The bell tower is located in La Fiesta Nacional de la Flor in Escobar, Buenos Aires, Argentina.
And this is the setup. 24 channels controller driven by a RaspberryPi using two IO Pi Zero hats, and the MIDI Keyboard connected to the setup, so we can play live, and also record songs.
Most of the "system" is implemented in carrillon.py, where Midi events are translated into GPIOs and also "menu options" to control the system to do things like recording a song, replaying a song, turning on and off the main air pressure pump, resetting the system or live playback.
The file live.py contains the mapping between Midi events and GPIO ports, and also a very crude live playback feature, mapping qwerty key presses to bells.
IOPi.py is a librarayr accompaning the IO Pi Zero boards, it requires python-smbus to access the I2C bus.
midi2tcp.py is a proxy that will create a virtual Midi port called "Carrillon" and then will listen on port 8383 for incoming TCP connections. When a client is connected, all incoming Midi messages will be forwarded to the TCP connection. It can handle only 1 TCP conneciton at a time, if a second connection is received while another client is connected, the second connection will be honored, and the first will be closed.
To try it very raw, you can use netcat (nc) and aplaymidi in three terminals, as in:
(term 1) $ python midi2tcp.py
Listening at port 8383
(term 2) $ nc -v 0 8383
Connection to 0 8383 port [tcp/*] succeeded!
(term 3) $ aconnect -l
client 0: 'System' [type=kernel]
0 'Timer '
1 'Announce '
client 14: 'Midi Through' [type=kernel]
0 'Midi Through Port-0'
client 128: 'RtMidiIn Client' [type=user,pid=14301]
0 'Carrillon '
(term 3) $ aplaymidi --port 128 anysong.mid
(term 1) $ ./midi2tcp.py
Listening at port 8383
Received connection from: ('127.0.0.1', 57012)
Listening at port 8383
Sending:L b'\x03\x92C]'
Sending:L b'\x03\x92C\x00'
Sending:L b'\x03\x92@]'
Sending:L b'\x03\x92@\x00'
^C
(term 2) $ nc -v 0 8383
Connection to 0 8383 port [tcp/*] succeeded!
�C]�C�@]�@
The project also depends on python-rtmidi and uses external aconnect, aplaymidi and arecordmidi from package alsa-utils to play and record songs.