蓝牙开发

代码：

private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                using (BluetoothClient client = new BluetoothClient())
                {
                    BluetoothDeviceInfo[] devices = client.DiscoverDevices();
                    Cursor.Current = Cursors.Default;
                    string deviceName = "";
                    BluetoothAddress deviceAddress = null;
                    if (devices != null && devices.Length > 0)
                    {
                        for (int i = 0; i < devices.Length; i++)
                        {
                            if (!string.IsNullOrEmpty(devices[i].DeviceName) && devices[i].DeviceName.ToLower().IndexOf("print") > -1)
                            {
                                deviceName = devices[i].DeviceName;
                                deviceAddress = devices[i].DeviceAddress;
                            }
                        }
                    }
                    client.SetPin(deviceAddress, "0000");
                    Guid service = BluetoothService.SerialPort;//BluetoothService.Handsfree
                    client.Connect(deviceAddress, service);
                    //client.Connect(deviceAddress, BluetoothService.SerialPort); //if connect to cell phone and so forth.
                    if (client.Connected)
                    {
                        //传输数据
                        string dataToSend = "Hello from service!";
                        byte[] dataBuffer = System.Text.ASCIIEncoding.ASCII.GetBytes(dataToSend);
                        using (NetworkStream stream = client.GetStream())
                        {
                            stream.Write(dataBuffer, 0, dataBuffer.Length);
                            stream.Flush();
                        }
                        client.Close();
                    }
                    else
                    {

                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Connect failed:" + ex.Message);
            }
        }

using：

using InTheHand.Net.Sockets;
using InTheHand.Net;
using InTheHand.Net.Bluetooth;

要引用的dll：InTheHand.Net.Personal.dll，
来源：

用C#调用蓝牙编程
https://www.cnblogs.com/sczw-maqing/p/3329750.html

蓝牙开发，有个第三方控件 32feet.NET
https://www.cnblogs.com/skyrickie/articles/1986571.html WinCE下32feet.NET进行蓝牙开发

https://bbs.csdn.net/topics/391955812 wince连接蓝牙打印机
https://www.cnblogs.com/procoder/archive/2009/05/14/Windows_Mobile_Bluetooth_32feet.html