App sync code, handles button presses from mixer and syncs changes from VM. Included python code from the mixer. Some other PCB changes, but still needs improvements

ControlMixerPython/boot.py

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+import board
+import digitalio
+import usb_mixer
+recovery_pin = digitalio.DigitalInOut(board.D3)
+recovery_pin.direction = digitalio.Direction.INPUT
+recovery_pin.pull = digitalio.Pull.UP
+
+if recovery_pin.value == True:
+    print("Booting normal mode")
+    usb_mixer.initUsb()
+else:
+    print("Booting recovery mode")

ControlMixerPython/boot_out.txt

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+Adafruit CircuitPython 9.0.4 on 2024-04-16; Adafruit ItsyBitsy M4 Express with samd51g19
+Board ID:itsybitsy_m4_express
+UID:A9C26FCF53324853202020472A3908FF
+boot.py output:
+Booting normal mode

ControlMixerPython/code.py

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+import usb_mixer
+import board
+import adafruit_dotstar
+import analogio
+import time
+import math
+import ulab.numpy
+import supervisor
+import key_interface
+import storage
+
+ANALOG_SAMPLE_SIZE=150
+
+pixel = adafruit_dotstar.DotStar(board.DOTSTAR_CLOCK, board.DOTSTAR_DATA, 1)
+slider_in = [
+    analogio.AnalogIn(board.A0),
+    analogio.AnalogIn(board.A1),
+    analogio.AnalogIn(board.A2),
+    analogio.AnalogIn(board.A3),
+    analogio.AnalogIn(board.A4)
+]
+
+i2c = board.I2C()
+keys = key_interface.KeyInterface(i2c)
+
+slider_vals = [0,0,0,0,0]
+buttons = [0,0,0,0,0]
+
+def readSlider(num):
+    vals = []
+    for i in range(0, ANALOG_SAMPLE_SIZE):
+        vals.append((slider_in[num].value / 0xFFFF) * 0xFFF) # Scale analogio back to ADC resolution
+    val_median = ulab.numpy.mean(ulab.numpy.ndarray(vals))
+    return math.floor((val_median / 0xFFF) * usb_mixer.RESOLUTION)
+
+try:
+    pixel.fill((0,0,32))
+    while not supervisor.runtime.usb_connected:
+        time.sleep(0.5)
+
+    mixer = usb_mixer.UsbMixer()
+    pixel.fill((0,32,0))
+    while True:
+        new_values = [
+            readSlider(0),
+            readSlider(1),
+            readSlider(2),
+            readSlider(3),
+            readSlider(4)
+        ]
+        new_buttons = keys.scan()
+        if new_values != slider_vals or new_buttons != buttons:
+            mixer.send_values(new_values[0], new_values[1], new_values[2], new_values[3], new_values[4], new_buttons)
+            pixel.fill((32,32,32))
+            slider_vals = new_values
+            buttons = new_buttons
+            pixel.fill((0,32,0))
+        time.sleep(0.001)
+except Exception as ex:
+    pixel.fill((255,0,0))
+    with open("/runtime_ex.txt", "w") as fp:
+        fp.write(ex)
+    print(ex)

ControlMixerPython/key_interface.py

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+import board
+import busio
+import digitalio
+from adafruit_mcp230xx.mcp23017 import MCP23017
+
+class KeyInterface:
+    _MCP23017_OLATA = 0x14
+    _MCP23017_OLATB = 0x15
+    
+    def set_olata(self, val: int):
+        self.mcp._write_u8(self._MCP23017_OLATA, val)
+    
+    def set_olatb(self, val: int):
+        self.mcp._write_u8(self._MCP23017_OLATB, val)
+    
+    def __init__(self, i2c):
+        self._i2c = i2c
+        
+        # Turn on MCP
+        self._mcp_reset_pin = digitalio.DigitalInOut(board.D4)
+        self._mcp_reset_pin.direction = digitalio.Direction.OUTPUT
+        self._mcp_reset_pin.value = True
+        
+        # Initialize MCP
+        self.mcp = MCP23017(self._i2c)
+        
+        # Set up MCP pins
+        self.mcp.iodirb = 255  # GPIO B (rows) all input
+        self.mcp.ipolb = 255   # GPIO B inverted polarity
+        self.mcp.gppub = 255   # GPIO B all pulled up
+        self.set_olata(0) # GPIO A all output low
+        
+    def scan(self):
+        result = []
+        for i in range(0, 6):
+            self.mcp.iodira = 0xFF ^ (0x01 << i)
+            result.append(self.mcp.gpiob)
+        self.mcp.iodira = 0xFF
+        return result
+        

ControlMixerPython/sd/placeholder.txt

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+SD cards mounted at /sd will hide this file from Python. SD cards are not visible via USB CIRCUITPY.

ControlMixerPython/usb_mixer.py

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+import usb_hid
+import supervisor
+import storage
+import usb_midi
+
+DEFAULT_REPORT_ID = 1
+HANDSHAKE_REPORT_ID = 2
+VENDOR_ID = 0x0359
+PRODUCT_ID = 0x6497           # T9 MIXR
+
+RESOLUTION = 100               # Voicemeeter sliders go from 12.0 to -60.0 in 0.1 increments
+
+REPORT_DESCRIPTOR = bytes([
+    0x05, 0x01,               # Usage Page (Generic Desktop Controls)
+    0x09, 0x08,               # Usage (Multi-Axis Controller)
+    #0x09, 0x04, # Joystick usage (for windows to pick up as usb controller)
+    0xA1, 0x01,               # Collection (Application)
+    # BUTTONS
+    0x05, 0x09,               # Usage Page (Button)
+    0x19, 0x01,               # Usage Minimum (Button 1)
+    0x29, 0x30,               # Usage Maximum (Button 48)
+    0x15, 0x00,               # Logical Minimum (0)
+    0x25, 0x01,               # Logical Maximum (1)
+    0x75, 0x01,               # Report Size (1 bit)
+    0x95, 0x30,               # Report Count (48)
+    0x81, 0x02,               # Input (Data, Variable, Absolute)
+    # SLIDERS
+    0x15, 0x00,               # Logical Minimum (0)
+    0x26, 0xFF, 0xFF,         # Logical Maximum (RESOLUTION (720))
+    0x75, 0x10,               # Report Size (16-bit)
+    #0x85, DEFAULT_REPORT_ID,  # Report ID (DEFAULT_REPORT_ID)
+    0x95, 0x05,               # Report Count (5)
+    0x09, 0x30,               # Usage (X)
+    0x09, 0x31,               # Usage (Y)
+    0x09, 0x32,               # Usage (Z)
+    0x09, 0x33,               # Usage (Rx)
+    0x09, 0x34,               # Usage (Ry)
+    0x81, 0x00,               # Input (Data, Array, Absolute)
+    0xC0,                     # End Collection
+    #0x05, 0x06,               # Usage Page (Generic Device Controls)
+    #0x09, 0x01,               # Usage (Background/Nonuser controls)
+    #0xA1, 0x01,               # Collection (Application)
+    #0x75, 0x20,               # Report Size (32-bit)
+    #0x95, 0x01,               # Report Count (1)
+    #0x85, HANDSHAKE_REPORT_ID,# Report ID (HANDSHAKE_REPORT_ID)
+    #0x81, 0x01,               # Input (Constant, Array, Absolute)
+    #0xC0,                     # End Collection
+])
+
+def initUsb():
+    if supervisor.runtime.usb_connected:
+        raise RuntimeError("USB cannot be initialized post-boot")
+    supervisor.set_usb_identification(manufacturer="TechAbsol", product="USB Mixer", vid=VENDOR_ID, pid=PRODUCT_ID)
+
+    usb_midi.disable()
+    usb_hid.set_interface_name("CircuitPython Mixer")
+    sliders = usb_hid.Device(
+        report_descriptor = REPORT_DESCRIPTOR,
+        usage_page=0x01,
+        usage=0x08,
+        report_ids=(0,),
+        in_report_lengths=(16,),
+        out_report_lengths=(0,),
+    )
+
+    #storage.disable_usb_drive()
+    #storage.remount("/", False)
+    usb_hid.enable((sliders,))
+    
+class UsbMixer():
+    def __init__(self):
+        if not supervisor.runtime.usb_connected:
+            raise RuntimeError("USB is not connected")
+        self._device = next((dev for dev in usb_hid.devices if dev.usage_page == 0x01 and dev.usage == 0x08))
+        if self._device is None:
+            raise RuntimeError("USB mixer doesn't appear to be initialized")
+
+    def _valToBytes(self, value):
+        return bytes([value & 0xFF, (value >> 8) & 0xFF])
+    
+    def _keysToBytes(self, keys):
+        return bytes([keys[0], keys[1], keys[2], keys[3], keys[4], keys[5]])
+
+    def send_values(self, slider1, slider2, slider3, slider4, slider5, keys):
+        report = self._keysToBytes(keys) + self._valToBytes(slider1) + self._valToBytes(slider2) + self._valToBytes(slider3) + self._valToBytes(slider4) + self._valToBytes(slider5)
+        self._device.send_report(report)