ESP connect via espressif BLE to WIN10python desktop APP via bleak but only send 1 time value

[ESCHICK]

Hello,

i want to use the espressif libary for BLE on ESP32 and for the desktop app i use bleak. I want to send a value SPO2 to the python terminal for the time the power on the ESP is on. But i only can connect for short time after turn the ESP on and it only display my SPO2 Value 1 time. Can someone help? Maybe someone know a good tutorial too?

The first Code for the ESP:

/*
    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleServer.cpp
    Ported to Arduino ESP32 by Evandro Copercini
    updates by chegewara
*/

#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

// See the following for generating UUIDs:
// https://www.uuidgenerator.net/

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

void setup() {
  Serial.begin(115200);
  Serial.println("Starting BLE work!");

  BLEDevice::init("Long name works now");
  BLEServer *pServer = BLEDevice::createServer(); // Erstelle Server 
  BLEService *pService = pServer->createService(SERVICE_UUID);
  BLECharacteristic *pCharacteristic = pService->createCharacteristic( // Erzeuge Charakteristik
                                         CHARACTERISTIC_UUID,
                                         BLECharacteristic::PROPERTY_READ |
                                         BLECharacteristic::PROPERTY_WRITE
                                       );

  pCharacteristic->setValue("Hello World says Neil");
  pService->start();
  // BLEAdvertising *pAdvertising = pServer->getAdvertising();  // this still is working for backward compatibility
  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);
  pAdvertising->setScanResponse(true);
  pAdvertising->setMinPreferred(0x06);  // functions that help with iPhone connections issue
  pAdvertising->setMinPreferred(0x12);
  BLEDevice::startAdvertising();
  Serial.println("Characteristic defined! Now you can read it in your phone!");
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(2000);
}

This is the code for the Python APP:

Libary: GitHub - hbldh/bleak: A cross platform Bluetooth Low Energy Client for Python using asyncio

and:

import asyncio
from bleak import BleakClient

address = "CC:50:E3:9C:15:02"
MODEL_NBR_UUID = "beb5483e-36e1-4688-b7f5-ea07361b26a8"

async def main(address):
    async with BleakClient(address) as client:
        model_number = await client.read_gatt_char(MODEL_NBR_UUID)
        print("Model Number: {0}".format("".join(map(chr, model_number))))

async def read_spo2(address):
    SPO2_UUID = "beb5483e-36e1-4688-b7f5-ea07361b26a8"
    async with BleakClient(address) as client:
        spo2_data = await client.read_gatt_char(SPO2_UUID)
        spo2_value = int.from_bytes(spo2_data, byteorder='little')
        print("SPO2: {0}".format(spo2_value))

async def main(address):
    await read_spo2(address)

asyncio.run(main(address))