midi to gameboy

code.py

import busio
import microcontroller
import time
import random
import _gbio
import adafruit_midi

# TimingClock is worth importing first if present as it
# will make parsing more efficient for this high frequency event
# Only importing what is used will save a little bit of memory
from adafruit_midi.timing_clock            import TimingClock
# from adafruit_midi.channel_pressure        import ChannelPressure
from adafruit_midi.control_change          import ControlChange
from adafruit_midi.note_off                import NoteOff
from adafruit_midi.note_on                 import NoteOn
# from adafruit_midi.pitch_bend_change       import PitchBendChange
# from adafruit_midi.polyphonic_key_pressure import PolyphonicKeyPressure
# from adafruit_midi.program_change          import ProgramChange
# from adafruit_midi.start                   import Start
# from adafruit_midi.stop                    import Stop
# from adafruit_midi.system_exclusive        import SystemExclusive
from adafruit_midi.midi_message import MIDIUnknownEvent

_gbio.reset_gameboy()

midi_out = busio.UART(microcontroller.pin.PB31, None, baudrate=31250)
midi_in = busio.UART(None, microcontroller.pin.PA00, baudrate=31250, timeout=0)

# for i in range(10):
#     midi_out.write(str(i).encode("utf-8"))
#     print(midi_in.read())
#     time.sleep(0.5)

# midi_inoutdemo - demonstrates receiving and sending MIDI events
midi = adafruit_midi.MIDI(midi_in=midi_in, midi_out=midi_out, in_channel=(0,1,2,3), out_channel=0)

print("Midi Demo in and out")

# Convert channel numbers at the presentation layer to the ones musicians use
print("Default output channel:", midi.out_channel + 1)
print("Listening on input channels:", tuple([c + 1 for c in midi.in_channel]))

import array
pitch_bits = array.array("B", [0]) * (128 * 2)

for i in range(128):
    f = 440 * 2 ** ((i-60+16) / 12)
    gb = 2048 - 131072 / f
    gb = max(0, int(round(gb)))
    pitch_bits[i * 2] = gb >> 8
    pitch_bits[i * 2 + 1] = gb & 0xff

on = (  b"\x00\x0e\x13" # Load 0x13 into C Increment fails for some reason
        #b"\x0c" # increment C
        b"\x3e\x83" # Load 0x83 into A
        b"\xe2" # Loads A into ff00 + C (0x13)

        b"\x0c" # increment C
        b"\x3e\x87" # Load 0x87 into A
        b"\xe2") # Loads A into ff00 + C (0x14)

current_note_bits = [0, 0]

def note_on(midi_note, *, voice=0):
    instructions = bytearray(on)

    # volume is slow to respond per note
    # instructions[7] = 0x03 | volume << 4

    if voice == 1:
        instructions[2] = 0x18

    instructions[4] = pitch_bits[midi_note * 2 + 1]
    instructions[8] = 0x80 | pitch_bits[midi_note * 2]
    current_note_bits[voice] = pitch_bits[midi_note * 2]
    gbio.queue_commands(instructions)

def note_off(midi_note, *, voice=0):
    instructions = bytearray(b"\x00\x0e\x12" # Load 0x13 into C Increment fails for some reason
                        b"\x3e\x00" # Load 0x83 into A
                        b"\xe2") # Loads A into ff00 + C (0x13)
    if voice == 1:
        instructions[2] = 0x19
    #instructions[4] |= current_note_bits[voice]
    #current_note_bits[voice] = 0
    gbio.queue_commands(instructions)

voice_settings = (  b"\x00\x0e\x11" # Load 0x11 into C Increment fails for some reason
        b"\x3e\x5f" # Load 0x3f into A
        b"\xe2" # Loads A into ff00 + C (0x16)

        b"\x0c" # increment C
        b"\x3e\x00" # Load 0x87 into A
        b"\xe2" # Loads A into ff00 + C (0x17)

        # Voice 2
        b"\x0e\x16" # Load 0x16 into C Increment fails for some reason
        b"\x3e\x5f" # Load 0x3f into A
        b"\xe2" # Loads A into ff00 + C (0x16)

        b"\x0c" # increment C
        b"\x3e\xf0" # Load 0x87 into A
        b"\xe2") # Loads A into ff00 + C (0x17)
_gbio.queue_commands(voice_settings)

voice_state = [0, 0]
while True:
    message = midi.receive()  # non-blocking read
    if not message:
        continue
    print(message)
    # For a Note On or Note Off play a major chord
    # For any other known event just forward it
    if isinstance(msg_in, NoteOn) and msg_in.velocity != 0:
        # print("On", msg_in.note,
        #       "from channel", channel_in + 1)
        if 0 in voice_state:
            free_voice = voice_state.index(0)
            note_on(msg_in.note, voice=free_voice)
            voice_state[free_voice] = msg_in.note
        else:
            # Busy, pass it on.
            midi.send(msg_in)

    elif (isinstance(msg_in, NoteOff) or
           isinstance(msg_in, NoteOn) and msg_in.velocity == 0):
        # print("Off", msg_in.note,
        #       "from channel", channel_in + 1)
        if msg_in.note in voice_state:
            active_voice = voice_state.index(msg_in.note)
            note_off(msg_in.note, voice=active_voice)
            voice_state[active_voice] = 0
        else:
            # We're not playing it, pass it on.
            midi.send(msg_in)
        # print(voice_state)
    elif isinstance(msg_in, MIDIUnknownEvent):
        # Message are only known if they are imported
        print("Unknown MIDI event status", msg_in.status)

    elif isinstance(msg_in, ControlChange):
        # Message are only known if they are imported
        print("Control change", msg_in.control, msg_in.value)
    elif isinstance(msg_in, TimingClock):
        pass
    elif msg_in is not None:
        print(msg_in)