The BLE Test Server can run in either "write back" mode or "data logging" mode. The default is "write back." The intent with these two modes is to simplify verification of what has been written to and read from the attribute.
In write back mode, the attribute value is initially empty. It must be written to before it can be read, and the value(s) read from the attribute will simply be what has been previously written to it.
In data logging mode, data written to the attribute are written to the TLOG. Similarly, all values read from the attribute are also logged.
Starts the BLE Test Server if it is not already running.
Stops the BLE Test Server.