8000 examples/bluetooth: Add example for reading temperature sensor. · rlangoy/micropython@0527baf · GitHub
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examples/bluetooth: Add example for reading temperature sensor.
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‎examples/bluetooth/ble_temperature_central.py

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# This example finds and connects to a BLE temperature sensor (e.g. the one in ble_temperature.py).
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import bluetooth
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import random
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import struct
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import time
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import micropython
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from ble_advertising import decode_services, decode_name
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from micropython import const
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_IRQ_CENTRAL_CONNECT = const(1 << 0)
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_IRQ_CENTRAL_DISCONNECT = const(1 << 1)
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_IRQ_GATTS_WRITE = const(1 << 2)
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_IRQ_GATTS_READ_REQUEST = const(1 << 3)
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_IRQ_SCAN_RESULT = const(1 << 4)
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_IRQ_SCAN_COMPLETE = const(1 << 5)
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_IRQ_PERIPHERAL_CONNECT = const(1 << 6)
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_IRQ_PERIPHERAL_DISCONNECT = const(1 << 7)
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_IRQ_GATTC_SERVICE_RESULT = const(1 << 8)
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_IRQ_GATTC_CHARACTERISTIC_RESULT = const(1 << 9)
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_IRQ_GATTC_DESCRIPTOR_RESULT = const(1 << 10)
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_IRQ_GATTC_READ_RESULT = const(1 << 11)
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_IRQ_GATTC_WRITE_STATUS = const(1 << 12)
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_IRQ_GATTC_NOTIFY = const(1 << 13)
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_IRQ_GATTC_INDICATE = const(1 << 14)
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_IRQ_ALL = const(0xffff)
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# org.bluetooth.service.environmental_sensing
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_ENV_SENSE_UUID = bluetooth.UUID(0x181A)
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# org.bluetooth.characteristic.temperature
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_TEMP_UUID = bluetooth.UUID(0x2A6E)
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_TEMP_CHAR = (_TEMP_UUID, bluetooth.FLAG_READ|bluetooth.FLAG_NOTIFY,)
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_ENV_SENSE_SERVICE = (_ENV_SENSE_UUID, (_TEMP_CHAR,),)
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# org.bluetooth.characteristic.gap.appearance.xml
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_ADV_APPEARANCE_GENERIC_THERMOMETER = const(768)
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class BLETemperatureCentral:
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def __init__(self, ble):
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self._ble = ble
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self._ble.active(True)
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self._ble.irq(handler=self._irq)
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self._reset()
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def _reset(self):
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# Cached name and address from a successful scan.
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self._name = None
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self._addr_type = None
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self._addr = None
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# Cached value (if we have one)
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self._value = None
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# Callbacks for completion of various operations.
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# These reset back to None after being invoked.
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self._scan_callback = None
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self._conn_callback = None
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self._read_callback = None
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# Persistent callback for when new data is notified from the device.
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self._notify_callback = None
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# Connected device.
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self._conn_handle = None
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self._value_handle = None
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def _irq(self, event, data):
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if event == _IRQ_SCAN_RESULT:
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addr_type, addr, connectable, rssi, adv_data = data
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if connectable and _ENV_SENSE_UUID in decode_services(adv_data):
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# Found a potential device, remember it and stop scanning.
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self._addr_type = addr_type
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self._addr = bytes(addr) # Note: The addr buffer is owned by modbluetooth, need to copy it.
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self._name = decode_name(adv_data) or '?'
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self._ble.gap_scan(None)
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elif event == _IRQ_SCAN_COMPLETE:
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if self._scan_callback:
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if self._addr:
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# Found a device during the scan (and the scan was explicitly stopped).
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self._scan_callback(self._addr_type, self._addr, self._name)
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self._scan_callback = None
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else:
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# Scan timed out.
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self._scan_callback(None, None, None)
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elif event == _IRQ_PERIPHERAL_CONNECT:
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# Connect successful.
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conn_handle, addr_type, addr, = data
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if addr_type == self._addr_type and addr == self._addr:
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self._conn_handle = conn_handle
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self._ble.gattc_discover_services(self._conn_handle)
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elif event == _IRQ_PERIPHERAL_DISCONNECT:
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# Disconnect (either initiated by us or the remote end).
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conn_handle, _, _, = data
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if conn_handle == self._conn_handle:
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# If it was initiated by us, it'll already be reset.
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self._reset()
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elif event == _IRQ_GATTC_SERVICE_RESULT:
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# Connected device returned a service.
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conn_handle, start_handle, end_handle, uuid = data
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if conn_handle == self._conn_handle and uuid == _ENV_SENSE_UUID:
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self._ble.gattc_discover_characteristics(self._conn_handle, start_handle, end_handle)
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elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
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# Connected device returned a characteristic.
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conn_handle, def_handle, value_handle, properties, uuid = data
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if conn_handle == self._conn_handle and uuid == _TEMP_UUID:
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self._value_handle = value_handle
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# We've finished connecting and discovering device, fire the connect callback.
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if self._conn_callback:
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self._conn_callback()
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elif event == _IRQ_GATTC_READ_RESULT:
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# A read completed successfully.
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conn_handle, value_handle, char_data = data
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if conn_handle == self._conn_handle and value_handle == self._value_handle:
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self._update_value(char_data)
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if self._read_callback:
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self._read_callback(self._value)
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self._read_callback = None
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elif event == _IRQ_GATTC_NOTIFY:
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# The ble_temperature.py demo periodically notifies its value.
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conn_handle, value_handle, notify_data = data
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if conn_handle == self._conn_handle and value_handle == self._value_handle:
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self._update_value(notify_data)
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if self._notify_callback:
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self._notify_callback(self._value)
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# Returns true if we've successfully connected and discovered characteristics.
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def is_connected(self):
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return self._conn_handle is not None and self._value_handle is not None
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# Find a device advertising the environmental sensor service.
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def scan(self, callback=None):
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self._addr_type = None
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self._addr = None
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self._scan_callback = callback
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self._ble.gap_scan(2000, 30000, 30000)
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# Connect to the specified device (otherwise use cached address from a scan).
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def connect(self, addr_type=None, addr=None, callback=None):
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self._addr_type = addr_type or self._addr_type
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self._addr = addr or self._addr
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self._conn_callback = callback
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if self._addr_type is None or self._addr is None:
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return False
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self._ble.gap_connect(self._addr_type, self._addr)
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return True
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# Disconnect from current device.
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def disconnect(self):
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if not self._conn_handle:
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return
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self._ble.gap_disconnect(self._conn_handle)
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self._reset()
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# Issues an (asynchronous) read, will invoke callback with data.
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def read(self, callback):
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if not self.is_connected():
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return
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self._read_callback = callback
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self._ble.gattc_read(self._conn_handle, self._value_handle)
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# Sets a callback to be invoked when the device notifies us.
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def on_notify(self, callback):
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self._notify_callback = callback
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def _update_value(self, data):
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# Data is sint16 in degrees Celsius with a resolution of 0.01 degrees Celsius.
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self._value = struct.unpack('<h', data)[0] / 100
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return self._value
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def value(self):
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return self._value
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def demo():
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ble = bluetooth.BLE()
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central = BLETemperatureCentral(ble)
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not_found = False
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def on_scan(addr_type, addr, name):
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if addr_type is not None:
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print('Found sensor:', addr_type, addr, name)
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central.connect()
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else:
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nonlocal not_found
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not_found = True
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print('No sensor found.')
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central.scan(callback=on_scan)
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# Wait for connection...
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while not central.is_connected():
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time.sleep_ms(100)
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if not_found:
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return
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print('Connected')
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# Explicitly issue reads, using "print" as the callback.
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while central.is_connected():
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central.read(callback=print)
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time.sleep_ms(2000)
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# Alternative to the above, just show the most recently notified value.
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# while central.is_connected():
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# print(central.value())
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# time.sleep_ms(2000)
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print('Disconnected')
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if __name__ == '__main__':
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demo()

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