Update remote characteristic value from a notification (#49)

* Add NimBLERemoteCharacteristic::getValue(time_t *timestamp = nullptr) to get the latest remote characteristic and (optionally) it's timestamp. 

* Added a timestamp to NimBLEAdvertisedDevice for the moment a device was scanned

Co-authored-by: h2zero <[email protected]>

Author: Jeroen88

src/NimBLEAdvertisedDevice.cpp

@@ -546,6 +546,11 @@ uint8_t NimBLEAdvertisedDevice::getAddressType() {
 }
 
 
+time_t NimBLEAdvertisedDevice::getTimestamp() {
+    return m_timestamp;
+}
+
+
 void NimBLEAdvertisedDevice::setAddressType(uint8_t type) {
     m_addressType = type;
 }

src/NimBLEAdvertisedDevice.h

@@ -55,7 +55,8 @@ class NimBLEAdvertisedDevice {
     uint8_t*        getPayload();
     size_t          getPayloadLength();
     uint8_t         getAddressType();
-    void setAddressType(uint8_t type);
+    time_t          getTimestamp();
+    void            setAddressType(uint8_t type);
 
 
     bool        isAdvertisingService(const NimBLEUUID &uuid);
@@ -111,6 +112,7 @@ class NimBLEAdvertisedDevice {
     uint8_t*        m_payload;
     size_t          m_payloadLength = 0;
     uint8_t         m_addressType;
+    time_t          m_timestamp;
 };
 
 /**

src/NimBLEClient.cpp

@@ -720,14 +720,18 @@ uint16_t NimBLEClient::getMTU() {
                 if(characteristic != cVector->cend()) {
                     NIMBLE_LOGD(LOG_TAG, "Got Notification for characteristic %s", (*characteristic)->toString().c_str());
 
+                    if((*characteristic)->m_semaphoreReadCharEvt.take(0, "notifyValue")) { 
+                        (*characteristic)->m_value = std::string((char *)event->notify_rx.om->om_data, event->notify_rx.om->om_len);
+                        (*characteristic)->m_timestamp = time(nullptr);
+                        (*characteristic)->m_semaphoreReadCharEvt.give();
+                    }
                     if ((*characteristic)->m_notifyCallback != nullptr) {
                         NIMBLE_LOGD(LOG_TAG, "Invoking callback for notification on characteristic %s",
                                              (*characteristic)->toString().c_str());
                         (*characteristic)->m_notifyCallback(*characteristic, event->notify_rx.om->om_data,
                                                             event->notify_rx.om->om_len,
                                                             !event->notify_rx.indication);
                     }
-
                     break;
                 }
             }

src/NimBLERemoteCharacteristic.cpp

@@ -60,6 +60,7 @@ static const char* LOG_TAG = "NimBLERemoteCharacteristic";
     m_notifyCallback     = nullptr;
     m_rawData            = nullptr;
     m_dataLen            = 0;
+    m_timestamp          = 0;
  } // NimBLERemoteCharacteristic
 
 
@@ -389,8 +390,6 @@ std::string NimBLERemoteCharacteristic::readValue() {
 
     int rc = 0;
     int retryCount = 1;
-    // Clear the value before reading.
-    m_value = "";
 
     NimBLEClient* pClient = getRemoteService()->getClient();
 
@@ -402,6 +401,8 @@ std::string NimBLERemoteCharacteristic::readValue() {
 
     do {
         m_semaphoreReadCharEvt.take("readValue");
+        // Clear the value before reading.
+        m_value = "";
 
         rc = ble_gattc_read_long(pClient->getConnId(), m_handle, 0,
                                  NimBLERemoteCharacteristic::onReadCB,
@@ -440,6 +441,21 @@ std::string NimBLERemoteCharacteristic::readValue() {
 } // readValue
 
 
+/**
+ * @brief Get the value of the remote characteristic.
+ * @return The value of the remote characteristic.
+ */
+std::string NimBLERemoteCharacteristic::getValue(time_t *timestamp) {
+    m_semaphoreReadCharEvt.take("getValue");
+    std::string value = m_value;
+    if(timestamp != nullptr) {
+        *timestamp = m_timestamp;
+    }
+    m_semaphoreReadCharEvt.give();
+    return value;
+}
+
+
 /**
  * @brief Callback for characteristic read operation.
  * @return 0 or error code.
@@ -462,6 +478,7 @@ int NimBLERemoteCharacteristic::onReadCB(uint16_t conn_handle,
             NIMBLE_LOGD(LOG_TAG, "Got %d bytes", attr->om->om_len);
 
             characteristic->m_value += std::string((char*) attr->om->om_data, attr->om->om_len);
+            characteristic->m_timestamp = time(nullptr);
             return 0;
         }
     }
@@ -509,7 +526,7 @@ bool NimBLERemoteCharacteristic::registerForNotify(notify_callback notifyCallbac
 /**
  * @brief Delete the descriptors in the descriptor vector.
  * We maintain a vector called m_descriptorVector that contains pointers to BLERemoteDescriptors
- * object references. Since we allocated these in this class, we are also responsible for deleteing
+ * object references. Since we allocated these in this class, we are also responsible for deleting
  * them. This method does just that.
  * @return N/A.
  */

src/NimBLERemoteCharacteristic.h

@@ -57,6 +57,7 @@ class NimBLERemoteCharacteristic {
     uint8_t                                        readUInt8();
     uint16_t                                       readUInt16();
     uint32_t                                       readUInt32();
+    std::string                                    getValue(time_t *timestamp = nullptr);
     bool                                           registerForNotify(notify_callback _callback,
                                                                      bool notifications = true,
                                                                      bool response = true);
@@ -105,6 +106,7 @@ class NimBLERemoteCharacteristic {
     uint8_t*                m_rawData;
     size_t                  m_dataLen;
     notify_callback         m_notifyCallback;
+    time_t                  m_timestamp;
 
     // We maintain a vector of descriptors owned by this characteristic.
     std::vector<NimBLERemoteDescriptor*> m_descriptorVector;

src/NimBLEScan.cpp

@@ -143,6 +143,7 @@ NimBLEScan::NimBLEScan() {
             advertisedDevice->parseAdvertisement(&fields);
             advertisedDevice->setScan(pScan);
             advertisedDevice->setAdvertisementResult(event->disc.data, event->disc.length_data);
+            advertisedDevice->m_timestamp = time(nullptr);
 
             if (pScan->m_pAdvertisedDeviceCallbacks) {
                 // If not active scanning report the result to the listener.