backports HWCDC to v2.0.15 (#9462)

* feat: backports HWCDC

* fix: statement order

* feat: Apply suggestions from code review

* Create HWCDC_Events.ino

* Create .skip.esp32

* Create .skip.esp32s2

* Delete libraries/ESP32/examples/HWSerial_Events/.skip.esp32s2

* Delete libraries/ESP32/examples/HWSerial_Events/.skip.esp32

* Delete libraries/ESP32/examples/HWSerial_Events/HWSerial_Events.ino

cores/esp32/HWCDC.h

@@ -42,6 +42,10 @@ typedef union {
 
 class HWCDC: public Stream
 {
+private:
+    static void deinit();
+    static bool isCDC_Connected();
+
 public:
     HWCDC();
     ~HWCDC();
@@ -64,6 +68,11 @@ public:
     size_t write(const uint8_t *buffer, size_t size);
     void flush(void);
     
+    static bool isPlugged(void);
+    inline static bool isConnected(void)
+    {
+        return isCDC_Connected();
+    }
     inline size_t read(char * buffer, size_t size)
     {
         return read((uint8_t*) buffer, size);

libraries/ESP32/examples/HWCDC_Events/.skip.esp32

+

libraries/ESP32/examples/HWCDC_Events/.skip.esp32s2

+

libraries/ESP32/examples/HWCDC_Events/HWCDC_Events.ino

+/*
+ * This Example demonstrates how to receive Hardware Serial Events
+ * This USB interface is available for the ESP32-S3 and ESP32-C3
+ * 
+ * It will log all events and USB status (plugged/unplugged) into UART0
+ * Any data read from UART0 will be sent to the USB CDC
+ * Any data read from USB CDC will be sent to the UART0
+ * 
+ * A suggestion is to use Arduino Serial Monitor for the UART0 port
+ * and some other serial monitor application for the USB CDC port
+ * in order to see the exchanged data and the Hardware Serial Events
+ * 
+ */
+
+#ifndef ARDUINO_USB_MODE
+#error This ESP32 SoC has no Native USB interface
+#elif ARDUINO_USB_MODE == 0
+#warning This sketch should be used when USB is in Hardware CDC and JTAG mode
+void setup(){}
+void loop(){}
+#else
+
+// Makes it work always using Serial0 as UART0 and USBSerial as the HW Serial USB CDC port
+#if ARDUINO_USB_CDC_ON_BOOT
+// HardwareSerial::Serial0 is declared but HWCDC::USBSerial not
+// Serial is the HWCDC USB CDC port
+#define USBSerial Serial
+#else
+// HWCDC::USBSerial is declared but HardwareSerial::Serial0 not
+// Serial is HardwareSerial UART0
+#define Serial0 Serial   // redefine the symbol Serial0 to the default Arduino
+#endif
+
+// USB Event Callback Function that will log CDC events into UART0
+static void usbEventCallback(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data) {
+  if (event_base == ARDUINO_HW_CDC_EVENTS) {
+    switch (event_id) {
+      case ARDUINO_HW_CDC_CONNECTED_EVENT:
+        Serial0.println("CDC EVENT:: ARDUINO_HW_CDC_CONNECTED_EVENT");
+        break;
+      case ARDUINO_HW_CDC_BUS_RESET_EVENT:
+        Serial0.println("CDC EVENT:: ARDUINO_HW_CDC_BUS_RESET_EVENT");
+        break;
+      case ARDUINO_HW_CDC_RX_EVENT:
+        Serial0.println("\nCDC EVENT:: ARDUINO_HW_CDC_RX_EVENT");
+        // sends all bytes read from USB Hardware Serial to UART0
+        while (USBSerial.available()) Serial0.write(USBSerial.read());
+        break;
+      case ARDUINO_HW_CDC_TX_EVENT:
+        Serial0.println("CDC EVENT:: ARDUINO_HW_CDC_TX_EVENT");
+        break;
+
+      default:
+        break;
+    }
+  }
+}
+
+const char* _hwcdc_status[] = {
+  " USB Plugged but CDC is NOT connected\r\n",
+  " USB Plugged and CDC is connected\r\n",
+  " USB Unplugged and CDC is NOT connected\r\n",
+  " USB Unplugged BUT CDC is connected :: PROBLEM\r\n",
+};
+
+const char* HWCDC_Status() {
+  int i = USBSerial.isPlugged() ? 0 : 2;
+  if(USBSerial.isConnected()) i += 1;
+  return _hwcdc_status[i];
+}
+
+void setup() {
+  USBSerial.onEvent(usbEventCallback);
+  USBSerial.begin();
+
+  Serial0.begin(115200);
+  Serial0.setDebugOutput(true);
+  Serial0.println("Starting...");
+}
+
+void loop() {
+  static uint32_t counter = 0;
+  
+  Serial0.print(counter);
+  Serial0.print(HWCDC_Status());
+
+  if (USBSerial) {
+    USBSerial.printf("  [%ld] connected\n\r", counter);
+  }
+  // sends all bytes read from UART0 to USB Hardware Serial
+  while (Serial0.available()) USBSerial.write(Serial0.read());
+  delay(1000);
+  counter++;
+}
+#endif