Add USB MIDI support to libraries/USB (#8166)

* Added USBMIDI support to libraries/USB

* Added MIDI examples to libraries/USB

* Added missing newline at end of file to MidiController.ino

* Added USBMIDI.cpp to CMake file

* Fix narrowing conversion warning in USBMIDI.cpp

* Fix incomplete initializers warning in USBMIDI.cpp

* Apply suggestions from code review

Co-authored-by: Lucas Saavedra Vaz <lucassvaz@yahoo.com.br>

* add skip files for C6+H2

* remove already patched workaroud for bug

* move #define to top of file

---------

Co-authored-by: Me No Dev <me-no-dev@users.noreply.github.com>
Co-authored-by: Lucas Saavedra Vaz <lucas.vaz@espressif.com>
Co-authored-by: Jan Procházka <90197375+P-R-O-C-H-Y@users.noreply.github.com>
Co-authored-by: Lucas Saavedra Vaz <lucassvaz@yahoo.com.br>

Author: 4 people

CMakeLists.txt

@@ -115,6 +115,7 @@ set(LIBRARY_SRCS
   libraries/Update/src/Updater.cpp
   libraries/Update/src/HttpsOTAUpdate.cpp
   libraries/USB/src/USBHID.cpp
+  libraries/USB/src/USBMIDI.cpp
   libraries/USB/src/USBHIDMouse.cpp
   libraries/USB/src/USBHIDKeyboard.cpp
   libraries/USB/src/USBHIDGamepad.cpp

libraries/USB/examples/MIDI/MidiController/.skip.esp32

@@ -0,0 +1,118 @@
+/*
+This is an example of a Simple MIDI Controller using an ESP32 with a native USB support stack (S2, S3,
+etc.).
+
+For a hookup guide and more information on reading the ADC, please see:
+https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/ (Note: This sketch uses GPIO05)
+
+For best results, it is recommended to add an extra offset resistor between VCC and the potentiometer.
+(For a standard 10kOhm potentiometer, 3kOhm - 4kOhm will do.)
+
+View this sketch in action on YouTube: https://youtu.be/Y9TLXs_3w1M
+*/
+#if ARDUINO_USB_MODE
+#warning This sketch should be used when USB is in OTG mode
+void setup() {}
+void loop() {}
+#else
+
+#include <math.h>
+
+#include "USB.h"
+#include "USBMIDI.h"
+USBMIDI MIDI;
+
+#define MIDI_NOTE_C4 64
+
+#define MIDI_CC_CUTOFF 74
+
+///// ADC & Controller Input Handling /////
+
+#define CONTROLLER_PIN 5
+
+// ESP32 ADC needs a ton of smoothing
+#define SMOOTHING_VALUE 1000
+static double controllerInputValue = 0;
+
+void updateControllerInputValue() {
+    controllerInputValue =
+        (controllerInputValue * (SMOOTHING_VALUE - 1) + analogRead(CONTROLLER_PIN)) / SMOOTHING_VALUE;
+}
+
+void primeControllerInputValue() {
+    for (int i = 0; i < SMOOTHING_VALUE; i++) {
+        updateControllerInputValue();
+    }
+}
+
+uint16_t readControllerValue() {
+    // Lower ADC input amplitude to get a stable value
+    return round(controllerInputValue / 12);
+}
+
+///// Button Handling /////
+
+#define BUTTON_PIN 0
+
+// Simple button state transition function with debounce
+// (See also: https://tinyurl.com/simple-debounce)
+#define PRESSED 0xff00
+#define RELEASED 0xfe1f
+uint16_t getButtonEvent() {
+    static uint16_t state = 0;
+    state = (state << 1) | digitalRead(BUTTON_PIN) | 0xfe00;
+    return state;
+}
+
+///// Arduino Hooks /////
+
+void setup() {
+    Serial.begin(115200);
+    MIDI.begin();
+    USB.begin();
+
+    primeControllerInputValue();
+}
+
+void loop() {
+    uint16_t newControllerValue = readControllerValue();
+    static uint16_t lastControllerValue = 0;
+
+    // Auto-calibrate the controller range
+    static uint16_t maxControllerValue = 0;
+    static uint16_t minControllerValue = 0xFFFF;
+
+    if (newControllerValue < minControllerValue) {
+        minControllerValue = newControllerValue;
+    }
+    if (newControllerValue > maxControllerValue) {
+        maxControllerValue = newControllerValue;
+    }
+
+    // Send update if the controller value has changed
+    if (lastControllerValue != newControllerValue) {
+        lastControllerValue = newControllerValue;
+
+        // Can't map if the range is zero
+        if (minControllerValue != maxControllerValue) {
+            MIDI.controlChange(MIDI_CC_CUTOFF,
+                               map(newControllerValue, minControllerValue, maxControllerValue, 0, 127));
+        }
+    }
+
+    updateControllerInputValue();
+
+    // Hook Button0 to a MIDI note so that we can observe
+    // the CC effect without the need for a MIDI keyboard.
+    switch (getButtonEvent()) {
+        case PRESSED:
+            MIDI.noteOn(MIDI_NOTE_C4, 64);
+            break;
+        case RELEASED:
+            MIDI.noteOff(MIDI_NOTE_C4, 0);
+            break;
+        default:
+            break;
+    }
+}
+#endif /* ARDUINO_USB_MODE */