Workaround to disable bluetooth on NRF52 (#4055)

* Workaround to allow bluetooth disable on NRF52

* Use miminum tx power for bluetooth

* Reorganize

* Instantiate nrf52Bluetooth correctly..

* Change log message

src/platform/nrf52/NRF52Bluetooth.cpp

@@ -215,6 +215,18 @@ void NRF52Bluetooth::shutdown()
     Bluefruit.Advertising.stop();
 }
 
+void NRF52Bluetooth::startDisabled()
+{
+    // Setup Bluetooth
+    nrf52Bluetooth->setup();
+
+    // Shutdown bluetooth for minimum power draw
+    Bluefruit.Advertising.stop();
+    Bluefruit.setTxPower(-40); // Minimum power
+
+    LOG_INFO("Disabling NRF52 Bluetooth. (Workaround: tx power min, advertising stopped)\n");
+}
+
 bool NRF52Bluetooth::isConnected()
 {
     return Bluefruit.connected(connectionHandle);

src/platform/nrf52/NRF52Bluetooth.h

@@ -8,6 +8,7 @@ class NRF52Bluetooth : BluetoothApi
   public:
     void setup();
     void shutdown();
+    void startDisabled();
     void resumeAdvertising();
     void clearBonds();
     bool isConnected();

src/platform/nrf52/main-nrf52.cpp

@@ -68,10 +68,29 @@ static const bool useSoftDevice = true; // Set to false for easier debugging
 #if !MESHTASTIC_EXCLUDE_BLUETOOTH
 void setBluetoothEnable(bool enable)
 {
-    if (enable && config.bluetooth.enabled) {
+    // For debugging use: don't use bluetooth
     if (!useSoftDevice) {
+        if (enable)
             LOG_INFO("DISABLING NRF52 BLUETOOTH WHILE DEBUGGING\n");
-        } else {
+        return;
+    }
+
+    // If user disabled bluetooth: init then disable advertising & reduce power
+    // Workaround. Avoid issue where device hangs several days after boot..
+    // Allegedly, no significant increase in power consumption
+    if (!config.bluetooth.enabled) {
+        static bool initialized = false;
+        if (!initialized) {
+            nrf52Bluetooth = new NRF52Bluetooth();
+            nrf52Bluetooth->startDisabled();
+            initBrownout();
+            initialized = true;
+        }
+        return;
+    }
+
+    if (enable) {
+        // If not yet set-up
         if (!nrf52Bluetooth) {
             LOG_DEBUG("Initializing NRF52 Bluetooth\n");
             nrf52Bluetooth = new NRF52Bluetooth();
@@ -79,17 +98,17 @@ void setBluetoothEnable(bool enable)
 
             // We delay brownout init until after BLE because BLE starts soft device
             initBrownout();
-            } else {
+        }
+        // Already setup, apparently
+        else
             nrf52Bluetooth->resumeAdvertising();
     }
-        }
+    // Disable (if previously set-up)
-    } else {
+    else if (nrf52Bluetooth)
-        if (nrf52Bluetooth) {
         nrf52Bluetooth->shutdown();
-        }
-    }
 }
 #else
+#warning NRF52 "Bluetooth disable" workaround does not apply to builds with MESHTASTIC_EXCLUDE_BLUETOOTH
 void setBluetoothEnable(bool enable) {}
 #endif
 /**