* refactor: new helpers/nrf52 dir

* RAK, startOTAUpdate()

src/MeshCore.h

@@ -41,6 +41,7 @@ public:
   virtual void onAfterTransmit() { }
   virtual void reboot() = 0;
   virtual uint8_t getStartupReason() const = 0;
+  virtual bool startOTAUpdate() { return false; }   // not supported
 };
 
 }

src/helpers/nrf52/RAK4631Board.cpp

@@ -0,0 +1,63 @@
+#include <Arduino.h>
+#include "RAK4631Board.h"
+
+#include <bluefruit.h>
+#include <Wire.h>
+
+static BLEDfu bledfu;
+
+static void connect_callback(uint16_t conn_handle)
+{
+    (void)conn_handle;
+    MESH_DEBUG_PRINTLN("BLE client connected");
+}
+
+static void disconnect_callback(uint16_t conn_handle, uint8_t reason)
+{
+    (void)conn_handle;
+    (void)reason;
+
+    MESH_DEBUG_PRINTLN("BLE client disconnected");
+}
+
+bool RAK4631Board::startOTAUpdate() {
+    // Config the peripheral connection with maximum bandwidth
+    // more SRAM required by SoftDevice
+    // Note: All config***() function must be called before begin()
+    Bluefruit.configPrphBandwidth(BANDWIDTH_MAX);
+    Bluefruit.configPrphConn(92, BLE_GAP_EVENT_LENGTH_MIN, 16, 16);
+
+    Bluefruit.begin(1, 0);
+    // Set max power. Accepted values are: -40, -30, -20, -16, -12, -8, -4, 0, 4
+    Bluefruit.setTxPower(4);
+    // Set the BLE device name
+    Bluefruit.setName("RAK4631_OTA");
+
+    Bluefruit.Periph.setConnectCallback(connect_callback);
+    Bluefruit.Periph.setDisconnectCallback(disconnect_callback);
+
+    // To be consistent OTA DFU should be added first if it exists
+    bledfu.begin();
+
+    // Set up and start advertising
+    // Advertising packet
+    Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
+    Bluefruit.Advertising.addTxPower();
+    Bluefruit.Advertising.addName();
+
+    /* Start Advertising
+     - Enable auto advertising if disconnected
+     - Interval:  fast mode = 20 ms, slow mode = 152.5 ms
+     - Timeout for fast mode is 30 seconds
+     - Start(timeout) with timeout = 0 will advertise forever (until connected)
+
+     For recommended advertising interval
+     https://developer.apple.com/library/content/qa/qa1931/_index.html
+    */
+    Bluefruit.Advertising.restartOnDisconnect(true);
+    Bluefruit.Advertising.setInterval(32, 244); // in unit of 0.625 ms
+    Bluefruit.Advertising.setFastTimeout(30);   // number of seconds in fast mode
+    Bluefruit.Advertising.start(0);             // 0 = Don't stop advertising after n seconds
+
+  return true;
+}

src/helpers/nrf52/RAK4631Board.h

@@ -3,8 +3,6 @@
 #include <MeshCore.h>
 #include <Arduino.h>
 
-#if defined(NRF52_PLATFORM)
-
 // LoRa radio module pins for RAK4631
 #define  P_LORA_DIO_1   47
 #define  P_LORA_NSS     42
@@ -61,6 +59,6 @@ public:
   void reboot() override {
     NVIC_SystemReset();
   }
-};
 
-#endif
+  bool startOTAUpdate() override;
+};