Pybricks BLE UART C#

Program.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using Windows.Devices.Bluetooth;
using Windows.Devices.Bluetooth.GenericAttributeProfile;
using Windows.Devices.Bluetooth.Advertisement;
using Windows.Security.Cryptography;
using Windows.Storage.Streams;
using Buffer = Windows.Storage.Streams.Buffer;
using System.IO;
using System.Runtime.InteropServices.WindowsRuntime;

namespace BluetoothTest
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var watcher = new BluetoothLEAdvertisementWatcher();
            watcher.Received += (s, e) =>
            {
                watcher.Stop();
                Console.WriteLine("found device {0} {1}", e.Advertisement.LocalName, e.BluetoothAddress);
                Task.Run(async () =>
                {
                Console.WriteLine("task");
                    try
                    {
                        var device = await BluetoothLEDevice.FromBluetoothAddressAsync(e.BluetoothAddress);
                        var services = await device.GetGattServicesAsync(BluetoothCacheMode.Uncached);
                        var service = services.Services.Single(x => x.Uuid == Guid.Parse("6e400001-b5a3-f393-e0a9-e50e24dcca9e"));
                        var characteristics = await service.GetCharacteristicsAsync();
                        var tx = characteristics.Characteristics.Single(x => x.Uuid == Guid.Parse("6e400003-b5a3-f393-e0a9-e50e24dcca9e"));
                        tx.ValueChanged += (s2, e2) =>
                        {
                            var value = CryptographicBuffer.ConvertBinaryToString(BinaryStringEncoding.Utf8, e2.CharacteristicValue);
                            Console.WriteLine(value);
                        };
                        var result = tx.WriteClientCharacteristicConfigurationDescriptorWithResultAsync(GattClientCharacteristicConfigurationDescriptorValue.Notify);
                        Console.WriteLine(result);
                        var rx = characteristics.Characteristics.Single(x => x.Uuid == Guid.Parse("6e400002-b5a3-f393-e0a9-e50e24dcca9e"));
                        var value = new Buffer(4) as IBuffer;
                        var writer = new DataWriter(value.AsStream().AsOutputStream()) { ByteOrder = ByteOrder.LittleEndian };
                        writer.WriteUInt32(4);
                        var writeResult = await rx.WriteValueWithResultAsync(value, GattWriteOption.WriteWithoutResponse);
                        value = CryptographicBuffer.ConvertStringToBinary("    ", BinaryStringEncoding.Utf8);
                        writeResult = await rx.WriteValueWithResultAsync(value, GattWriteOption.WriteWithoutResponse);
                        value = CryptographicBuffer.ConvertStringToBinary("1234567890123456789012345678901234567890", BinaryStringEncoding.Utf8);
                        writeResult = await rx.WriteValueWithResultAsync(value, GattWriteOption.WriteWithoutResponse);
                        Console.WriteLine(writeResult.Status);
                    } catch (Exception ex)
                    {
                        Console.WriteLine(ex);
                    }
                });
            };
            watcher.Start();
            await Task.Delay(-1);
        }
    }
}