simple midi uart example for TrellisM4 in CircuitPython

TrellisM4_Simple_MIDI_UART/trellism4_simple_midi_uart.py

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+# Simple example of sending MIDI via UART to classic DIN-5 (not USB) synth
+
+import adafruit_trellism4
+
+import board
+import busio
+midiuart = busio.UART(board.SDA, board.SCL, baudrate=31250)
+print("MIDI UART EXAMPLE")
+
+trellis = adafruit_trellism4.TrellisM4Express()
+
+def wheel(pos):
+    if pos < 0 or pos > 255:
+        return 0, 0, 0
+    if pos < 85:
+        return int(255 - pos * 3), int(pos * 3), 0
+    if pos < 170:
+        pos -= 85
+        return 0, int(255 - pos * 3), int(pos * 3)
+    pos -= 170
+    return int(pos * 3), 0, int(255 - (pos * 3))
+
+
+for x in range(trellis.pixels.width):
+    for y in range(trellis.pixels.height):
+        pixel_index = (((y * 8) + x) * 256 // 2)
+        trellis.pixels[x, y] = wheel(pixel_index & 255)
+
+current_press = set()
+
+while True:
+    pressed = set(trellis.pressed_keys)
+
+    for press in pressed - current_press:
+        x, y = press
+        print("Pressed:", press)
+        noteval = 36 + x + (y * 8)
+        midiuart.write(bytes([0x90, noteval, 100]))
+
+    for release in current_press - pressed:
+        x, y = release
+        print("Released:", release)
+        noteval = 36 + x + (y * 8)
+        midiuart.write(bytes([0x90, noteval, 0]))  # note off
+
+    current_press = pressed