* added helpers/ArduinoSerialInterface, for the 'companion radio'

* .ini, target envs: Heltec_v3_companion_radio_usb &  Heltec_v3_companion_radio_ble

src/helpers/ArduinoSerialInterface.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "BaseSerialInterface.h"
+#include <Arduino.h>
+
+class ArduinoSerialInterface : public BaseSerialInterface {
+  bool _isEnabled;
+  uint8_t _state;
+  uint8_t _frame_len;
+  uint8_t rx_len;
+  HardwareSerial* _serial;
+  uint8_t rx_buf[MAX_FRAME_SIZE];
+
+public:
+  ArduinoSerialInterface() { _isEnabled = false; _state = 0; }
+
+  void begin(HardwareSerial& serial) { _serial = &serial; }
+
+  // BaseSerialInterface methods
+  void enable() override;
+  void disable() override;
+  bool isEnabled() const override { return _isEnabled; }
+
+  bool isConnected() const override;
+
+  bool isWriteBusy() const override;
+  size_t writeFrame(const uint8_t src[], size_t len) override;
+  size_t checkRecvFrame(uint8_t dest[]) override;
+};