98 lines
3.0 KiB
Python
98 lines
3.0 KiB
Python
# This example demonstrates a simple temperature sensor peripheral.
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#
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# The sensor's local value updates every second, and it will notify
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# any connected central every 10 seconds.
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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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from ble_advertising import advertising_payload
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from micropython import const
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_IRQ_CENTRAL_CONNECT = const(1)
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_IRQ_CENTRAL_DISCONNECT = const(2)
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_IRQ_GATTS_INDICATE_DONE = const(20)
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_FLAG_READ = const(0x0002)
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_FLAG_NOTIFY = const(0x0010)
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_FLAG_INDICATE = const(0x0020)
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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_CHAR = (
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bluetooth.UUID(0x2A6E),
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_FLAG_READ | _FLAG_NOTIFY | _FLAG_INDICATE,
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)
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_ENV_SENSE_SERVICE = (
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_ENV_SENSE_UUID,
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(_TEMP_CHAR,),
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)
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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 BLETemperature:
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def __init__(self, ble, name="mpy-temp"):
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self._ble = ble
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self._ble.active(True)
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self._ble.irq(self._irq)
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((self._handle,),) = self._ble.gatts_register_services((_ENV_SENSE_SERVICE,))
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self._connections = set()
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self._payload = advertising_payload(
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name=name, services=[_ENV_SENSE_UUID], appearance=_ADV_APPEARANCE_GENERIC_THERMOMETER
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)
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self._advertise()
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def _irq(self, event, data):
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# Track connections so we can send notifications.
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if event == _IRQ_CENTRAL_CONNECT:
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conn_handle, _, _ = data
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self._connections.add(conn_handle)
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elif event == _IRQ_CENTRAL_DISCONNECT:
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conn_handle, _, _ = data
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self._connections.remove(conn_handle)
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# Start advertising again to allow a new connection.
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self._advertise()
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elif event == _IRQ_GATTS_INDICATE_DONE:
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conn_handle, value_handle, status = data
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def set_temperature(self, temp_deg_c, notify=False, indicate=False):
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# Data is sint16 in degrees Celsius with a resolution of 0.01 degrees Celsius.
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# Write the local value, ready for a central to read.
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self._ble.gatts_write(self._handle, struct.pack("<h", int(temp_deg_c * 100)))
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if notify or indicate:
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for conn_handle in self._connections:
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if notify:
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# Notify connected centrals.
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self._ble.gatts_notify(conn_handle, self._handle)
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if indicate:
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# Indicate connected centrals.
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self._ble.gatts_indicate(conn_handle, self._handle)
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def _advertise(self, interval_us=500000):
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self._ble.gap_advertise(interval_us, adv_data=self._payload)
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def demo():
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ble = bluetooth.BLE()
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temp = BLETemperature(ble)
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t = 25
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i = 0
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while True:
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# Write every second, notify every 10 seconds.
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i = (i + 1) % 10
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temp.set_temperature(t, notify=i == 0, indicate=False)
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# Random walk the temperature.
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t += random.uniform(-0.5, 0.5)
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time.sleep_ms(1000)
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if __name__ == "__main__":
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demo()
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