Add SerialDualInterface that allows ble companions to be used over usb while ble is disconnected

examples/companion_radio/main.cpp

@@ -43,7 +43,8 @@ static uint32_t _atoi(const char* sp) {
     #endif
   #elif defined(BLE_PIN_CODE)
     #include <helpers/esp32/SerialBLEInterface.h>
-    SerialBLEInterface serial_interface;
+    #include <helpers/SerialDualInterface.h>
+    SerialDualInterface<SerialBLEInterface> serial_interface;
   #elif defined(SERIAL_RX)
     #include <helpers/ArduinoSerialInterface.h>
     ArduinoSerialInterface serial_interface;
@@ -73,7 +74,8 @@ static uint32_t _atoi(const char* sp) {
 #elif defined(NRF52_PLATFORM)
   #ifdef BLE_PIN_CODE
     #include <helpers/nrf52/SerialBLEInterface.h>
-    SerialBLEInterface serial_interface;
+    #include <helpers/SerialDualInterface.h>
+    SerialDualInterface<SerialBLEInterface> serial_interface;
   #else
     #include <helpers/ArduinoSerialInterface.h>
     ArduinoSerialInterface serial_interface;
@@ -151,7 +153,7 @@ void setup() {
   );
 
 #ifdef BLE_PIN_CODE
-  serial_interface.begin(BLE_NAME_PREFIX, the_mesh.getNodePrefs()->node_name, the_mesh.getBLEPin());
+  serial_interface.begin(BLE_NAME_PREFIX, the_mesh.getNodePrefs()->node_name, the_mesh.getBLEPin(), Serial);
 #else
   serial_interface.begin(Serial);
 #endif
@@ -198,7 +200,7 @@ void setup() {
   WiFi.begin(WIFI_SSID, WIFI_PWD);
   serial_interface.begin(TCP_PORT);
 #elif defined(BLE_PIN_CODE)
-  serial_interface.begin(BLE_NAME_PREFIX, the_mesh.getNodePrefs()->node_name, the_mesh.getBLEPin());
+  serial_interface.begin(BLE_NAME_PREFIX, the_mesh.getNodePrefs()->node_name, the_mesh.getBLEPin(), Serial);
 #elif defined(SERIAL_RX)
   companion_serial.setPins(SERIAL_RX, SERIAL_TX);
   companion_serial.begin(115200);

examples/companion_radio/ui-new/UITask.cpp

@@ -220,7 +220,7 @@ class HomeScreen : public UIScreen {
         display.setTextSize(1);
         display.drawTextCentered(display.width() / 2, 43, "< Connected >");
 
-      } else if (the_mesh.getBLEPin() != 0) { // BT pin
+      } else if (the_mesh.getBLEPin() != 0 && _task->isSerialEnabled()) { // BT pin
         display.setColor(DisplayDriver::RED);
         display.setTextSize(2);
         sprintf(tmp, "Pin:%d", the_mesh.getBLEPin());

src/helpers/ArduinoSerialInterface.cpp

@@ -13,8 +13,12 @@ void ArduinoSerialInterface::disable() {
   _isEnabled = false;
 }
 
-bool ArduinoSerialInterface::isConnected() const { 
-  return true;   // no way of knowing, so assume yes
+bool ArduinoSerialInterface::isConnected() const {
+#if defined(NRF52_PLATFORM) || defined(ESP32_PLATFORM)
+  return Serial;   // operator bool() checks connection (USB CDC DTR, UART init)
+#else
+  return true;     // platforms without operator bool() on Serial have no way of knowing, so assume yes
+#endif
 }
 
 bool ArduinoSerialInterface::isWriteBusy() const {

src/helpers/SerialDualInterface.h

@@ -0,0 +1,73 @@
+#pragma once
+
+#include "ArduinoSerialInterface.h"
+
+template <typename BLEInterface>
+class SerialDualInterface : public BaseSerialInterface {
+  BLEInterface _ble;
+  ArduinoSerialInterface _usb;
+  bool _bleWasConnected;
+
+public:
+  SerialDualInterface() : _bleWasConnected(false) { }
+
+  void begin(const char* prefix, char* name, uint32_t pin_code, Stream& serial) {
+    _ble.begin(prefix, name, pin_code);
+    _usb.begin(serial);
+  }
+
+  // enable/disable only control BLE, USB is always available
+  void enable() override {
+    _ble.enable();
+  }
+
+  void disable() override {
+    _ble.disable();
+  }
+
+  bool isEnabled() const override {
+    return _ble.isEnabled() || _usb.isEnabled();
+  }
+
+  bool isConnected() const override {
+    return _ble.isConnected() || _usb.isConnected();
+  }
+
+  bool isWriteBusy() const override {
+    if (_ble.isConnected()) return _ble.isWriteBusy();
+    return _usb.isWriteBusy();
+  }
+
+  size_t writeFrame(const uint8_t src[], size_t len) override {
+    if (_ble.isConnected()) return _ble.writeFrame(src, len);
+    return _usb.writeFrame(src, len);
+  }
+
+  size_t checkRecvFrame(uint8_t dest[]) override {
+    // Always call BLE first, it needs polling for send queue draining
+    // and advertising watchdog, even when USB is the active transport
+    size_t n = _ble.checkRecvFrame(dest);
+
+    bool bleNow = _ble.isConnected();
+    if (bleNow != _bleWasConnected) {
+      if (bleNow) {
+        // BLE just connected, wait for any pending USB write to finish
+        while (_usb.isWriteBusy()) { }
+        _usb.disable();
+      } else {
+        // BLE just disconnected, re-enable USB (resets state machine,
+        // discarding any stale bytes from the previous session)
+        _usb.enable();
+      }
+      _bleWasConnected = bleNow;
+    }
+
+    if (n > 0) return n;  // got a BLE frame
+
+    // Only check USB when BLE is not connected
+    if (!bleNow) {
+      return _usb.checkRecvFrame(dest);
+    }
+    return 0;
+  }
+};