first commit walkmellotron code

Walkmellotron/code.py

@@ -0,0 +1,45 @@
+# SPDX-FileCopyrightText: 2022 John Park for Adafruit Industries
+# SPDX-License-Identifier: MIT
+
+import time
+import board
+import busio
+import adafruit_mcp4728
+import usb_midi
+import adafruit_midi
+from adafruit_midi.note_on import NoteOn
+
+i2c = busio.I2C(board.SCL1, board.SDA1)  # qt py rp2040 amirite
+mcp4728 = adafruit_mcp4728.MCP4728(i2c)
+
+FULL_VREF_RAW_VALUE = 4095
+
+mcp4728.channel_a.raw_value = FULL_VREF_RAW_VALUE
+mcp4728.channel_a.vref = adafruit_mcp4728.Vref.INTERNAL
+mcp4728.channel_a.gain = 2
+
+time.sleep(1)  # settle
+volts_per_note = 0.0833  # 1/12th V for 1V/Oct
+
+def midi_to_mv(note):
+    notemv = 1000 * (note * volts_per_note)
+    return int(notemv)
+
+
+midi = adafruit_midi.MIDI(
+    midi_in=usb_midi.ports[0], in_channel=0, midi_out=usb_midi.ports[1], out_channel=0
+)
+
+
+while True:
+    msg = midi.receive()
+    if msg is not None:
+        if isinstance(msg, NoteOn):
+            string_msg = 'NoteOn'
+            #  get note number
+            string_val = str(msg.note)
+            # print("\nnote:",string_val)
+            if msg.note < 32:
+                mv = midi_to_mv(msg.note)
+                # print(mv*0.001, "V")
+                mcp4728.channel_a.raw_value = (mv)