Data exchange between C# SerialPort and Java Android Phone

Developers commonly use serial ports as a means of exchanging data between devices. In this article, we will explore how to establish a communication channel between a C# application running on a Windows computer and a Java Android phone, using the SerialPort class and the UsbSerial library.

Prerequisites

Before we get started, make sure you have the following prerequisites:

• A Windows computer with a serial port.
• Visual Studio or another C# development environment.
• A Java development environment, such as Android Studio.
• An Android phone with a USB port.

Setting up the C# application

To communicate with the Android phone, we’ll use the SerialPort class in C#. Here’s how to set it up:

1. Open Visual Studio and create a new C# project.
2. Add a reference to the System.IO.Ports namespace.
3. In the Form_Load event, create an instance of the SerialPort class and configure it with the appropriate settings, such as the port name, baud rate, and data bits.

using System.IO.Ports;

private void Form1_Load(object sender, EventArgs e)
{
    SerialPort serialPort = new SerialPort("COM1", 9600, Parity.None, 8, StopBits.One);
    serialPort.Open();
}In the Form_Closing event, close the serial port:

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    serialPort.Close();
}Setting up the Android application

To communicate with the C# application, we’ll use the UsbSerial library in Java. Here’s how to set it up:

1. Open Android Studio and create a new Android project.
2. Add the following dependency to your app-level build.gradle file:

• dependencies { implementation 'com.github.felHR85:UsbSerial:6.1.3

dependencies {
    implementation 'com.github.felHR85:UsbSerial:6.1.3'
}In the onCreate method of your main activity, create an instance of the UsbSerialDevice class and configure it with the appropriate settings, such as the baud rate and data bits:

import com.felhr.usbserial.*;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
    UsbDevice usbDevice = ... // get a reference to the USB device
    UsbSerialDevice serialDevice = UsbSerialDevice.createUsbSerialDevice(usbDevice, usbManager);
    serialDevice.open();
    serialDevice.setBaudRate(9600);
    serialDevice.setDataBits(UsbSerialInterface.DATA_BITS_8);
}

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1. To send and receive data, use the read and write methods:

byte[] data = "@temasre".getBytes();
serialDevice.write(data);

byte[] buffer = new byte[16];
int numBytes = serialDevice.read(buffer);
String receivedData = new String(buffer, 0, numBytes);

Conclusion

In this article, we explored how to establish a communication channel between a C# application running on a Windows computer and a Java Android phone, using the SerialPort class and the UsbSerial library. By exchanging data over a serial port, you can enable your applications to communicate with a wide range of devices, such as sensors, actuators, and other micro