micropython aioble basic peripheral (service environmental_sensing with temperature characteristic)

main.py

import uasyncio as aio
import aioble
from bluetooth import UUID

import random
import struct

# org.bluetooth.service.environmental_sensing
_ENV_SENSE_UUID = UUID(0x181A)
# org.bluetooth.characteristic.temperature
_ENV_SENSE_TEMP_UUID = UUID(0x2A6E)
# org.bluetooth.characteristic.gap.appearance.xml
_ADV_APPEARANCE_GENERIC_THERMOMETER = 768


# Register GATT server
temp_service = aioble.Service(_ENV_SENSE_UUID)
temp_characteristic = aioble.Characteristic(temp_service, _ENV_SENSE_TEMP_UUID, read=True, notify=True)
aioble.register_services(temp_service)


# periodically polling a hardware sensor
async def sensor_task():
    while True:
        t = 25.5 + random.uniform(-0.5, 0.5)
        t_encode = struct.pack('<h', int(t * 100))
        temp_characteristic.write(t_encode, send_update=True)
        await aio.sleep_ms(1_000)


# wait for connections (don't advertise while a central is connected)
async def peripheral_task():
    while True:
        connection = await aioble.advertise(interval_us=250_000, name='mpy-temp',
                                            services=[_ENV_SENSE_UUID], appearance=_ADV_APPEARANCE_GENERIC_THERMOMETER)
        print('Connection from', connection.device)
        await connection.disconnected(timeout_ms=None)
        print('end of connection')


# create asyncio task and run it
loop = aio.get_event_loop()
loop.create_task(sensor_task())
loop.create_task(peripheral_task())
loop.run_forever()