Previously we used the service end handle or, if available, the handle of the next characteristic in the service
as the end handle when retrieving the descriptors of a characteristic. This process would fail when connecting to some
devices if the characteristics were retrieved individually instead of all together. The cause of failure was requesting
a handle range that is out of characteristic scope which is also out of line with BLE
specifications.
The fix included in this is to set the end handles of the characteristics either after retrieving all the characteristics
in a service by using the next charactertistic definition handle or, if the characteristic was retrieved separately,
we retrieve the next characteristic just before retrieving the descriptors.
Also adds:
* NimBLEScan::setDuplicateFilter() to tell the controller to filter duplicates
before sending the result to the host.
* NimBLEScan::setLimitedOnly() to tell the controller only report scan results
from devices advertising in limited discovery mode, i.e. directed advertising.
* NimBLEScan::setFilterPolicy() to set the filter policy i.e whitelist only devices.
* Replace all semaphores with task notifications.
* use critical sections to prevent concurrent data access.
* Ensure scan stop has been called before connecting.
* Optimize and cleanup
* Add template casting to NimBLERemoteDescriptor::readValue()
* Removed storage of the descriptor value read as it did not serve any purpose.
* Add subscribe() and unsubscribe() methods to replace registerForNotify() in NimBLERemoteCharacteristic.
* registerForNotify() remains as a (depreciated) method.
* Make remote attribute delete functions public.
* Rename clear...() functions to delete...(), with ... equals Service(-s), Characteristic(-s) or Descriptor(-s), depending on what the function actually deletes
Previously getRawData() made an unnecessary copy of the remote characteristic value data in order to return a uint8_t*. The resources used for this was unjustified by the value it provided as templates to retrieve such data have been added. Also the application writer could cast the std::string result of readValue() and/or getValue() however they choose using the data() method on the container if desired.
getDataLength() is also an unnecessary function as the length can be retrieved by the returned std::string from readValue() and/or getValue() with the length() method.
The value returned by reading a remote characteristic or by getting a notification for it is kept in the class instance of the NimBLERemoteCharacteristic. This value can be accessed as a std::string type using the getValue() function.
This adds templates to read the value in the type used by the peripheral. The same functionality is implemented for getting the manufacturer data or the service data of an advertised device.
* 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
Instead of discovering the peripheral database on connection and consuming
the associated resources this will give the user more control over the
discovery operation.
* Adds void NimBLEClient::discoverAtrributes() for the user to discover all
the peripheral attributes as a replacement for the former functionality.
* getServices(), getCharacteristics(), getDescriptors() now take an
optional bool parameter (default false).
If true it will clear the respective vector and retrieve all the respective
attributes from the peripheral. If false it will retrieve the attributes
only if the vector is empty, otherwise the vector is returned with the
currently stored attributes.
* getService(NimBLEUUID), getCharacteristic(NimBLEUUID), getDescriptor(NimBLEUUID)
will now check the respective vectors for the attribute object and, if not
found, will retrieve (only) the specified attribute from the peripheral.
Add iterators for NimBLEScan: NimBLEadvertisedDevice, NimBLEClient: NimBLERemoteService, NimBLERemoteService: NimBLERemoteCharacteristic and NimBLERemoteCharacteristic: NimBLERemoteDescriptor
This is handy e.g. for showing every address of the advertised devices from a scan. To do so, first get a new scan and next:
```
for(auto pAdvertisedDevice: pBLEScan->getResults()) {
Serial.printf("Address is %s\n", std::string(pAdvertisedDevice->getAddress()).c_str());
}
```
Of course any other property of the advertised device can be shown (or looked up, if that is your use case)
Also this is handy e.g. for showing every UUID in a peripheral. To do so, first connect to a peripheral and next:
```
for(auto pService: *pClient) {
Serial.printf("Service UUID is %s\n", std::string(pService->getUUID()).c_str());
for(auto pCharacteristic: *pService) {
Serial.printf("Characteristic UUID is %s\n", std::string(pCharacteristic->getUUID()).c_str());
for(auto pDescriptor: *pCharacteristic) {
Serial.printf("Descriptor UUID is %s\n", std::string(pDescriptor->getUUID()).c_str());
}
}
}
```
Again of course any other property can be shown, or looked up.
* Exchange map for vector, saving 1,076 bytes of program memory and 5,024 bytes of heap for a small device (LYWSD03MMC)
* Removing m_characteristicMapByHandle (using the handles form m_characteristicVector instead) saving in total (compared to the current master) 1,508 bytes of program memory and 6,500 bytes of heap for a small device (LYWSD03MMC)
* Change NimBLEScan container from std::map to std::vector
* Add function to get advertised device by address
* Update documentation
This allows NimBLE options in menuconfig to reduce code size based on
the roles selected (scan/advertising/central/peripheral).
Significant code space can be saved by removing unnecessary roles for the application.
