Get the raw RSSI device (if connected).
- macOS 10.7+
Returns the raw RSSI of the device.
This value is the perceived RSSI value, not relative the the golden range (see getRSSI for that value). This value will not available on all Bluetooth modules. If the value cannot be read (e.g. the device is disconnected) or is not available on a module, a value of +127 will be returned.