title: Bluetooth Low Energy - sending packets very slow
body: <p>We're building both a BLE device, and the mobile app to talk to it.  The mobile app is written in Xamarin/C#, with the Android stuff in an Android-specific PCL (Portable Class Library).</p>
  
  <p>I've split my data into small chunks so it fits into the default 20-byte BLE packet size, I've got one data block that is 96 bytes long so I send it as 6 16-byte data packets.  I've set it up so the first 5 data blocks are sent with WriteType set to GattWriteType.NoResponse, and only the last data block has WriteType set to GattWriteType.Default.</p>
  
  <p>For each of the first 5 data blocks I call SetValue() and WriteCharacteristic() and then wait for the OnCharacteristicWrite() notification to come before writing the next data block.  Doing this, I can write the first 5 data blocks in about 20 msec.  But then the 6th block (Write_With_Response) takes about 300 msec between the WriteCharacteristic() and the corresponding OnCharacteristicWrite() notification.</p>
  
  <p>Is this an expected delay?  It seems awfully long!</p>
  
  <p>Are there settings I need to tweak, to get the BLE write to happen faster?</p>