protected async Task StopUpdatesNativeAsync()
{
_gattCallback.CharacteristicValueUpdated -= OnCharacteristicValueChanged;
await TaskBuilder.EnqueueOnMainThreadAsync(() =>
{
if (!_gatt.SetCharacteristicNotification(NativeCharacteristic, false))
{
throw new CharacteristicReadException("GATT: SetCharacteristicNotification to false, FAILED.");
}
});
if (NativeCharacteristic.Descriptors.Count > 0)
{
var descriptors = await GetDescriptorsAsync();
var descriptor = descriptors.FirstOrDefault(d => d.Id.Equals(ClientCharacteristicConfigurationDescriptorId)) ??
descriptors.FirstOrDefault(); // fallback just in case manufacturer forgot
if (descriptor != null && (Properties.HasFlag(CharacteristicPropertyType.Notify) || Properties.HasFlag(CharacteristicPropertyType.Indicate)))
{
await descriptor.WriteAsync(BluetoothGattDescriptor.DisableNotificationValue.ToArray());
Trace.Message("Descriptor set value: DISABLE_NOTIFY");
}
}
else
{
Trace.Message("StopUpdatesNativeAsync descriptor set value FAILED: _nativeCharacteristic.Descriptors was empty");
}
}
protected async Task StartUpdatesNativeAsync()
{
// wire up the characteristic value updating on the gattcallback for event forwarding
_gattCallback.CharacteristicValueUpdated -= OnCharacteristicValueChanged;
_gattCallback.CharacteristicValueUpdated += OnCharacteristicValueChanged;
await TaskBuilder.EnqueueOnMainThreadAsync(() =>
{
if (!_gatt.SetCharacteristicNotification(NativeCharacteristic, true))
{
throw new CharacteristicReadException("Gatt SetCharacteristicNotification FAILED.");
}
});
// In order to subscribe to notifications on a given characteristic, you must first set the Notifications Enabled bit
// in its Client Characteristic Configuration Descriptor. See https://developer.bluetooth.org/gatt/descriptors/Pages/DescriptorsHomePage.aspx and
// https://developer.bluetooth.org/gatt/descriptors/Pages/DescriptorViewer.aspx?u=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
// for details.
if (NativeCharacteristic.Descriptors.Count > 0)
{
var descriptors = await GetDescriptorsAsync();
var descriptor = descriptors.FirstOrDefault(d => d.Id.Equals(ClientCharacteristicConfigurationDescriptorId)) ??
descriptors.FirstOrDefault(); // fallback just in case manufacturer forgot
// has to have one of these (either indicate or notify)
if (descriptor != null && Properties.HasFlag(CharacteristicPropertyType.Indicate))
{
await descriptor.WriteAsync(BluetoothGattDescriptor.EnableIndicationValue.ToArray());
Trace.Message("Descriptor set value: INDICATE");
}
if (descriptor != null && Properties.HasFlag(CharacteristicPropertyType.Notify))
{
await descriptor.WriteAsync(BluetoothGattDescriptor.EnableNotificationValue.ToArray());
Trace.Message("Descriptor set value: NOTIFY");
}
}
else
{
Trace.Message("Descriptor set value FAILED: _nativeCharacteristic.Descriptors was empty");
}
Trace.Message("Characteristic.StartUpdates, successful!");
}
