add simple arpeggiator example

Author: todbot

examples/tmidi_simple_arpeggiator.py

@@ -0,0 +1,58 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 Tod Kurt
+#
+# SPDX-License-Identifier: MIT
+
+# This example shows both receiving and sending MIDI messages
+# by implementing a simple arpeggiator.
+# MIDI notes send to MIDI In are arpeggiated to MIDI Output.
+
+import time
+import usb_midi
+import tmidi
+
+midi = tmidi.MIDI(midi_in=usb_midi.ports[0], midi_out=usb_midi.ports[1])
+# if serial midi
+# uart = busio.UART(rx=board.RX, tx=board.TX, timeout=0.000)
+# midi = tmidi.MIDI(midi_in=uart, midi_out=uart)
+
+tempo = 120  # bpm
+notes_per_beat = 2  # 1 = quarter-note, 2 = 8th, 4 = 16th
+note_time = 60 / tempo / notes_per_beat
+gate_percent = 0.5
+
+pressed_notes = []
+note_i = 0
+last_note_time = 0
+gate_time = 0
+while True:
+    # handle midi input
+    if msg := midi.receive():
+        if msg.type == tmidi.NOTE_ON and msg.velocity > 0:
+            print("note on", msg)
+            pressed_notes.append(msg.note)
+        elif msg.type == tmidi.NOTE_OFF or (
+            msg.type == tmidi.NOTE_ON and msg.velocity == 0
+        ):
+            if msg.note in pressed_notes:
+                midi.send(msg)  # send the note off
+                pressed_notes.remove(msg.note)
+                note_i = 0
+
+    # do midi output
+    if len(pressed_notes) == 0:
+        continue
+
+    now = time.monotonic()
+    if now - last_note_time >= note_time:
+        last_note_time = now
+        note_on = tmidi.Message(tmidi.NOTE_ON, pressed_notes[note_i], 127)
+        print("arp note_on: ", note_on)
+        midi.send(note_on)
+        gate_time = note_time * gate_percent
+
+    if gate_time > 0 and now - last_note_time >= gate_time:
+        gate_time = 0
+        note_off = tmidi.Message(tmidi.NOTE_OFF, pressed_notes[note_i], 127)
+        print("arp note_off:", note_off)
+        midi.send(note_off)
+        note_i = (note_i + 1) % len(pressed_notes)

tmidi.py

@@ -144,7 +144,6 @@
 }
 
 
-# pylint: disable=chained-comparison
 def _is_channel_message(status_byte):
     return status_byte >= NOTE_OFF and status_byte < SYSEX
 
@@ -202,7 +201,6 @@ class Message:
               print("note off:", msg.note, msg.velocity)
             elif msg.type == tmidi.PROGRAM_CHANGE:
               print("program change:", msg.value)
-
     """
 
     def __init__(self, mtype=SYSTEM_RESET, data0=0, data1=0, channel=0):
@@ -226,7 +224,6 @@ def __bytes__(self):
     def __repr__(self):
         return self.__str__()
 
-    # pylint: disable=consider-using-f-string
     def __str__(self):
         mtype = self.type
         type_str = "Message(" + _MSG_TYPE_NAMES.get(mtype, "Unknown")
@@ -403,7 +400,6 @@ def receive(self):
 
         return message
 
-    # pylint: disable=unnecessary-dunder-call
     def send(self, msg, channel=None):
         """Send a MIDI message.