Custom CircuitPython BLE Service

code.py

import board
import os
import time

from adafruit_ble import Service
from adafruit_ble import BLERadio
from adafruit_ble.advertising import Advertisement
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.characteristics import Characteristic
from adafruit_ble.characteristics.int import Uint16Characteristic
from adafruit_ble.uuid import VendorUUID


class CountdownClockService(Service):
    """Countdown Clock Service"""
    
    uuid					=	VendorUUID("F1B8ED4E-648B-4689-8A0C-4930BC3A2325")
    countdownStart			=	Uint16Characteristic(max_value = 9 * 60 + 59,
                                                     uuid = VendorUUID("955CB941-F229-4AAB-81FB-44349AFB6CA7"),
                                                     properties = Characteristic.WRITE | Characteristic.READ)
    
    def __init__(
        self,
        countdownStart = 10
    ) -> None:
        super().__init__(
            manufacturer = "Latency: Zero, LLC",
            software_revision = "1.0",
            model_number = "CC",
            serial_number = "12345",
            firmware_revision = "1.0",
            hardware_revision = "1.0",
        )


gBLE = BLERadio()
gBLE.name = "Countdown Clock BLE"
gService = CountdownClockService()
gAdv = ProvideServicesAdvertisement(gService)
#gAdv = Advertisement()
gAdv.short_name = "ClockSvc"

def BLETask():
    gBLE.stop_advertising()
    while True:
        gBLE.start_advertising(gAdv)
        print("Advertising")
        while not gBLE.connected:
            time.sleep(0.100)
            pass
        
        print("Stopping Advertising")
        gBLE.stop_advertising()
        while gBLE.connected:
            print("BLE connected")
            cs = gService.countdownStart
            if cs is not None:
                print(f"countdown start is { cs }")
            
            time.sleep(0.500)
    
while True:
    BLETask()

print("main exited")