[BREAKING] - Refactor NimBLEScan

* General code cleanup
* `NimBLEScan::start` will no longer clear cache or results if scanning is already in progress.
* `NimBLEScan::clearResults` will now reset the vector capacity to 0.
* `NimBLEScan::stop` will no longer call the `onScanEnd` callback as the caller should know its been stopped when this is called.
* `NimBLEScan::clearDuplicateCache` has been removed as it was problematic and only for the esp32. Stop and start the scanner for the same effect.
* `NimBLEScan::start` takes a new bool parameter `restart`, default `true`, that will restart an already in progress scan and clear the duplicate filter so all devices will be discovered again.
* Scan response data that is received without advertisement first will now create the device and send a callback.
* Added new method: `NimBLEAdvertisedDevice::isScannable()` that returns true if the device is scannable.
* Added default callbacks for `NimBLEScanCallbacks`
* `NimBLEScanCallbacks` function signatures updated:
* - `onDiscovered` now takes a `const NimBLEAdvertisedDevice*`
* - `onResult` now takes a `const NimBLEAdvertisedDevice*`
* - `onScanEnd` now takes a `const NimBLEScanResults&` and `int reason`
* Added new erase overload: `NimBLEScan::erase(const NimBLEAdvertisedDevice* device)`
* `NimBLEScanResults::getDevice` methods now return `const NimBLEAdvertisedDevice*`
* `NimBLEScanResults` iterators are now `const_iterator`

Author: h2zero

examples/Bluetooth_5/NimBLE_extended_client/NimBLE_extended_client.ino

@@ -16,7 +16,7 @@
 #define SERVICE_UUID        "ABCD"
 #define CHARACTERISTIC_UUID "1234"
 
-static NimBLEAdvertisedDevice* advDevice;
+static const NimBLEAdvertisedDevice* advDevice;
 static bool doConnect = false;
 static uint32_t scanTime = 10 * 1000; // In milliseconds, 0 = scan forever
 
@@ -40,7 +40,7 @@ class ClientCallbacks : public NimBLEClientCallbacks {
 /* Define a class to handle the callbacks when advertisements are received */
 class scanCallbacks: public NimBLEScanCallbacks {
 
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
         Serial.printf("Advertised Device found: %s\n", advertisedDevice->toString().c_str());
         if(advertisedDevice->isAdvertisingService(NimBLEUUID("ABCD")))
         {
@@ -55,8 +55,8 @@ class scanCallbacks: public NimBLEScanCallbacks {
     }
 
     /** Callback to process the results of the completed scan or restart it */
-    void onScanEnd(NimBLEScanResults results) {
-        Serial.println("Scan Ended");
+    void onScanEnd(const NimBLEScanResults& results, int reason) {
+        Serial.print("Scan Ended; reason = "); Serial.println(reason);
     }
 };
 

examples/NimBLE_Async_Client/NimBLE_Async_Client.ino

@@ -25,7 +25,7 @@ class ClientCallbacks : public NimBLEClientCallbacks {
 } clientCB;
 
 class scanCallbacks : public NimBLEScanCallbacks {
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
         Serial.printf("Advertised Device found: %s\n", advertisedDevice->toString().c_str());
         if (advertisedDevice->haveName() && advertisedDevice->getName() == "NimBLE-Server") {
             Serial.println("Found Our Device");
@@ -48,8 +48,8 @@ class scanCallbacks : public NimBLEScanCallbacks {
         }
     }
 
-    void onScanEnd(NimBLEScanResults results) {
-        Serial.println("Scan Ended");
+    void onScanEnd(const NimBLEScanResults& results, int reason) {
+        Serial.print("Scan Ended; reason = "); Serial.println(reason);
         NimBLEDevice::getScan()->start(scanTimeMs);
     }
 };

examples/NimBLE_Client/NimBLE_Client.ino

@@ -10,7 +10,7 @@
 
 #include <NimBLEDevice.h>
 
-static NimBLEAdvertisedDevice* advDevice;
+static const NimBLEAdvertisedDevice* advDevice;
 
 static bool doConnect = false;
 static uint32_t scanTime = 0 * 1000; // In milliseconds, 0 = scan forever
@@ -85,7 +85,7 @@ class ClientCallbacks : public NimBLEClientCallbacks {
 /** Define a class to handle the callbacks when advertisments are received */
 class scanCallbacks: public NimBLEScanCallbacks {
 
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
         Serial.print("Advertised Device found: ");
         Serial.println(advertisedDevice->toString().c_str());
         if(advertisedDevice->isAdvertisingService(NimBLEUUID("DEAD")))
@@ -101,8 +101,8 @@ class scanCallbacks: public NimBLEScanCallbacks {
     }
 
     /** Callback to process the results of the completed scan or restart it */
-    void onScanEnd(NimBLEScanResults results) {
-        Serial.println("Scan Ended");
+    void onScanEnd(const NimBLEScanResults& results, int reason) {
+        Serial.print("Scan Ended; reason = "); Serial.println(reason);
     }
 };
 

examples/NimBLE_Scan_Continuous/NimBLE_Scan_Continuous.ino

@@ -1,71 +1,49 @@
-/** Example of continuous scanning for BLE advertisements.
- * This example will scan forever while consuming as few resources as possible
- * and report all advertisments on the serial monitor.
+/**
+ *  Continuous Scan Example
+ *
+ *  This example demonstrates how to continuously scan for BLE devices.
+ *  When devices are found the onDiscovered and onResults callbacks will be called with the device data.
+ *  The scan will not store the results, only the callbacks will be used
+ *  When the scan timeout is reached the onScanEnd callback will be called and the scan will be restarted.
+ *  This will clear the duplicate cache in the controller and allow the same devices to be reported again.
  *
  * Created: on January 31 2021
  *      Author: H2zero
- *
  */
 
 #include "NimBLEDevice.h"
 
-NimBLEScan* pBLEScan;
+static constexpr uint32_t scanTime = 30 * 1000; // 30 seconds scan time.
 
-class scanCallbacks: public NimBLEScanCallbacks {
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
-      Serial.printf("Advertised Device: %s \n", advertisedDevice->toString().c_str());
+class scanCallbacks : public NimBLEScanCallbacks {
+    // Initial discovery, advertisement data only.
+    void onDiscovered(const NimBLEAdvertisedDevice* advertisedDevice) override {
+        Serial.printf("Discovered Device: %s\n", advertisedDevice->toString().c_str());
     }
-};
-
-void setup() {
-  Serial.begin(115200);
-  Serial.println("Scanning...");
-
-/** *Optional* Sets the filtering mode used by the scanner in the BLE controller.
- *
- *  Can be one of:
- *  CONFIG_BTDM_SCAN_DUPL_TYPE_DEVICE (0) (default)
- *  Filter by device address only, advertisements from the same address will be reported only once.
- *
- *  CONFIG_BTDM_SCAN_DUPL_TYPE_DATA (1)
- *  Filter by data only, advertisements with the same data will only be reported once,
- *  even from different addresses.
- *
- *  CONFIG_BTDM_SCAN_DUPL_TYPE_DATA_DEVICE (2)
- *  Filter by address and data, advertisements from the same address will be reported only once,
- *  except if the data in the advertisement has changed, then it will be reported again.
- *
- *  Can only be used BEFORE calling NimBLEDevice::init.
-*/
-  NimBLEDevice::setScanFilterMode(CONFIG_BTDM_SCAN_DUPL_TYPE_DEVICE);
 
-/** *Optional* Sets the scan filter cache size in the BLE controller.
- *  When the number of duplicate advertisements seen by the controller
- *  reaches this value it will clear the cache and start reporting previously
- *  seen devices. The larger this number, the longer time between repeated
- *  device reports. Range 10 - 1000. (default 20)
- *
- *  Can only be used BEFORE calling NimBLEDevice::init.
- */
-  NimBLEDevice::setScanDuplicateCacheSize(200);
+    // If active scanning the result here will have the scan response data.
+    // If not active scanning then this will be the same as onDiscovered.
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) override {
+        Serial.printf("Device result: %s\n", advertisedDevice->toString().c_str());
+    }
 
-  NimBLEDevice::init("");
+    void onScanEnd(const NimBLEScanResults& results, int reason) override {
+        Serial.printf("Scan ended reason = %d; restarting scan\n", reason);
+        NimBLEDevice::getScan()->start(scanTime, false, true);
+    }
+} scanCallbacks; // create a callback class instance.
 
-  pBLEScan = NimBLEDevice::getScan(); //create new scan
-  // Set the callback for when devices are discovered, no duplicates.
-  pBLEScan->setScanCallbacks(new scanCallbacks(), false);
-  pBLEScan->setActiveScan(true); // Set active scanning, this will get more data from the advertiser.
-  pBLEScan->setInterval(97); // How often the scan occurs / switches channels; in milliseconds,
-  pBLEScan->setWindow(37);  // How long to scan during the interval; in milliseconds.
-  pBLEScan->setMaxResults(0); // do not store the scan results, use callback only.
+void setup() {
+    Serial.begin(115200);
+    NimBLEDevice::init("");                         // Initialize the device, you can specify a device name if you want.
+    NimBLEScan* pBLEScan = NimBLEDevice::getScan(); // Create the scan object.
+    pBLEScan->setScanCallbacks(&scanCallbacks, false); // Set the callback for when devices are discovered, no duplicates.
+    pBLEScan->setActiveScan(true);          // Set active scanning, this will get more data from the advertiser.
+    pBLEScan->setMaxResults(0);             // Do not store the scan results, use callback only.
+    pBLEScan->start(scanTime, false, true); // duration, not a continuation of last scan, restart to get all devices again.
+    Serial.println("Scanning...");
 }
 
 void loop() {
-  // If an error occurs that stops the scan, it will be restarted here.
-  if(pBLEScan->isScanning() == false) {
-      // Start scan with: duration = 0 seconds(forever), no scan end callback, not a continuation of a previous scan.
-      pBLEScan->start(0, false);
-  }
-
-  delay(2000);
-}
+    delay(2000);
+}

examples/NimBLE_active_passive_scan/NimBLE_active_passive_scan.ino

@@ -12,16 +12,16 @@ bool active = false;
 
 class scanCallbacks: public NimBLEScanCallbacks {
 
-    void onDiscovered(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onDiscovered(const NimBLEAdvertisedDevice* advertisedDevice) {
       Serial.printf("Discovered Advertised Device: %s \n", advertisedDevice->toString().c_str());
     }
 
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
       Serial.printf("Advertised Device Result: %s \n", advertisedDevice->toString().c_str());
     }
 
-    void onScanEnd(NimBLEScanResults results){
-        Serial.println("Scan Ended");
+    void onScanEnd(const NimBLEScanResults& results, int reason) {
+        Serial.print("Scan Ended; reason = "); Serial.println(reason);
         active = !active;
         pBLEScan->setActiveScan(active);
         Serial.printf("scan start, active = %u\n", active);

examples/Refactored_original_examples/BLE_client/BLE_client.ino

@@ -22,7 +22,9 @@ static boolean doConnect = false;
 static boolean connected = false;
 static boolean doScan = false;
 static BLERemoteCharacteristic* pRemoteCharacteristic;
-static BLEAdvertisedDevice* myDevice;
+/* const required now */
+/* static BLEAdvertisedDevice* myDevice;*/
+static const BLEAdvertisedDevice* myDevice;
 
 static void notifyCallback(
   BLERemoteCharacteristic* pBLERemoteCharacteristic,
@@ -128,9 +130,9 @@ class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
    * Called for each advertising BLE server.
    */
 
-/*** Only a reference to the advertised device is passed now
+/*** Only a const pointer to the advertised device is passed now
   void onResult(BLEAdvertisedDevice advertisedDevice) { **/
-  void onResult(BLEAdvertisedDevice* advertisedDevice) {
+  void onResult(const BLEAdvertisedDevice* advertisedDevice) {
     Serial.print("BLE Advertised Device found: ");
     Serial.println(advertisedDevice->toString().c_str());
 

examples/Refactored_original_examples/BLE_scan/BLE_scan.ino

@@ -18,9 +18,9 @@ int scanTime = 5 * 1000; // In milliseconds, 0 = scan forever
 BLEScan* pBLEScan;
 
 class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
-  /*** Only a reference to the advertised device is passed now
+  /*** Only a const pointer to the advertised device is passed now
     void onResult(BLEAdvertisedDevice advertisedDevice) { **/
-    void onResult(BLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const BLEAdvertisedDevice* advertisedDevice) {
   /** Serial.printf("Advertised Device: %s \n", advertisedDevice.toString().c_str()); **/
       Serial.printf("Advertised Device: %s \n", advertisedDevice->toString().c_str());
     }

src/NimBLEAdvertisedDevice.cpp

@@ -757,6 +757,14 @@ bool NimBLEAdvertisedDevice::isConnectable() const {
     return (m_advType & BLE_HCI_ADV_CONN_MASK) || (m_advType & BLE_HCI_ADV_DIRECT_MASK);
 } // isConnectable
 
+/**
+ * @brief Check if this device is advertising as scannable.
+ * @return True if the device is scannable.
+ */
+bool NimBLEAdvertisedDevice::isScannable() const {
+    return isLegacyAdvertisement() && (m_advType == BLE_HCI_ADV_TYPE_ADV_IND || m_advType == BLE_HCI_ADV_TYPE_ADV_SCAN_IND);
+} // isScannable
+
 /**
  * @brief Check if this advertisement is a legacy or extended type
  * @return True if legacy (Bluetooth 4.x), false if extended (bluetooth 5.x).

src/NimBLEAdvertisedDevice.h

@@ -82,6 +82,7 @@ class NimBLEAdvertisedDevice {
     bool                 haveType(uint16_t type) const;
     std::string          toString() const;
     bool                 isConnectable() const;
+    bool                 isScannable() const;
     bool                 isLegacyAdvertisement() const;
 # if CONFIG_BT_NIMBLE_EXT_ADV
     uint8_t  getSetId() const;

src/NimBLEDevice.cpp

@@ -723,15 +723,7 @@ void NimBLEDevice::onReset(int reason) {
 
     m_synced = false;
 
-    NIMBLE_LOGE(LOG_TAG, "Resetting state; reason=%d, %s", reason, NimBLEUtils::returnCodeToString(reason));
-
-# if defined(CONFIG_BT_NIMBLE_ROLE_OBSERVER)
-    if (m_initialized) {
-        if (m_pScan != nullptr) {
-            m_pScan->onHostReset();
-        }
-    }
-# endif
+    NIMBLE_LOGE(LOG_TAG, "Host reset; reason=%d, %s", reason, NimBLEUtils::returnCodeToString(reason));
 } // onReset
 
 /**