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# This example demonstrates a simple temperature sensor peripheral.
#
# The sensor's local value updates every second, and it will notify
# any connected central every 10 seconds.
import bluetooth
import random
import struct
import time
from ble_advertising import advertising_payload
from micropython import const
_IRQ_CENTRAL_CONNECT = const(1 << 0)
_IRQ_CENTRAL_DISCONNECT = const(1 << 1)
# org.bluetooth.service.environmental_sensing
_ENV_SENSE_UUID = bluetooth.UUID(0x181A)
# org.bluetooth.characteristic.temperature
_TEMP_CHAR = (bluetooth.UUID(0x2A6E), bluetooth.FLAG_READ|bluetooth.FLAG_NOTIFY,)
_ENV_SENSE_SERVICE = (_ENV_SENSE_UUID, (_TEMP_CHAR,),)
# org.bluetooth.characteristic.gap.appearance.xml
_ADV_APPEARANCE_GENERIC_THERMOMETER = const(768)
class BLETemperature:
def __init__(self, ble, name='mpy-temp'):
self._ble = ble
self._ble.active(True)
self._ble.irq(handler=self._irq)
((self._handle,),) = self._ble.gatts_register_services((_ENV_SENSE_SERVICE,))
self._connections = set()
self._payload = advertising_payload(name=name, services=[0x181A], appearance=_ADV_APPEARANCE_GENERIC_THERMOMETER)
self._advertise()
def _irq(self, event, data):
# Track connections so we can send notifications.
if event == _IRQ_CENTRAL_CONNECT:
conn_handle, _, _, = data
self._connections.add(conn_handle)
elif event == _IRQ_CENTRAL_DISCONNECT:
conn_handle, _, _, = data
self._connections.remove(conn_handle)
# Start advertising again to allow a new connection.
self._advertise()
def set_temperature(self, temp_deg_c, notify=False):
# Data is sint16 in degrees Celsius with a resolution of 0.01 degrees Celsius.
# Write the local value, ready for a central to read.
self._ble.gatts_write(self._handle, struct.pack('<h', int(temp_deg_c * 100)))
if notify:
for conn_handle in self._connections:
# Notify connected centrals to issue a read.
self._ble.gatts_notify(conn_handle, self._handle)
def _advertise(self, interval_us=500000):
self._ble.gap_advertise(interval_us, adv_data=self._payload)
def demo():
ble = bluetooth.BLE()
temp = BLETemperature(ble)
t = 25
i = 0
while True:
# Write every second, notify every 10 seconds.
i = (i + 1) % 10
temp.set_temperature(t, notify=i == 0)
# Random walk the temperature.
t += random.uniform(-0.5, 0.5)
time.sleep_ms(1000)
if __name__ == '__main__':
demo()
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