func startScan() {

guard centralManager.state == .poweredOn else { return }

let uuid = CBUUID(string: "FFE0")

centralManager.scanForPeripherals(withServices: [uuid], option: nil)

let peripherals = centralManager.retrieveConnetedPeripherals(withServices: [uuid])

for peripheral in peripherals {

delegate.serialDidDiscoverPeripheral(peripheral, RSSI: nil)

}

}

func stopScan() {

centralManager.stopScan()

}

func connectToPeripheral(_peripheral: CBPeripheral) {

pendingPeripheral = peripheral

centralManager.connect(peripheral, options: nil)

}

func disconnect() {

if let p = connectedPeripheral {

centralManager.cancelPeripheralConnection(p)

} else if let p = pendingPeripheral {

centralManager.cancelPeripheralConnection(p)

}

}