usb-serial-for-android
mik3y
2020
Visit GitHub RepoUSB

usb-serial-for-android

This is a driver library for communication with Arduinos and other USB serial hardware on Android, using the Android USB Host API available on Android 3.1+.

No root access, ADK, or special kernel drivers are required; all drivers are implemented in Java. You get a raw serial port with read(), write(), and other basic functions for use with your own protocols.

Quick Start

1. Link your project to the library.

2. Copy device_filter.xml to your project's res/xml/ directory.

3. Configure your AndroidManifest.xml to notify your app when a device is attached (see Android USB Host documentation for help).

<activity
    android:name="..."
    ...>
  <intent-filter>
    <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
  </intent-filter>
  <meta-data
      android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
      android:resource="@xml/device_filter" />
</activity>

4. Use it! Example code snippet:

// Find all available drivers from attached devices.
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
List<UsbSerialDriver> availableDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(manager);
if (availableDrivers.isEmpty()) {
  return;
}

// Open a connection to the first available driver.
UsbSerialDriver driver = availableDrivers.get(0);
UsbDeviceConnection connection = manager.openDevice(driver.getDevice());
if (connection == null) {
  // You probably need to call UsbManager.requestPermission(driver.getDevice(), ..)
  return;
}

// Read some data! Most have just one port (port 0).
UsbSerialPort port = driver.getPorts().get(0);
try {
  port.open(connection);
  port.setParameters(115200, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);

  byte buffer[] = new byte[16];
  int numBytesRead = port.read(buffer, 1000);
  Log.d(TAG, "Read " + numBytesRead + " bytes.");
} catch (IOException e) {
  // Deal with error.
} finally {
  port.close();
}

For a more complete example, see the UsbSerialExamples project in git, which is a simple application for reading and showing serial data.

A simple Arduino application is also available which can be used for testing.

Probing for Unrecognized Devices

Sometimes you may need to do a little extra work to support devices which usb-serial-for-android doesn't [yet] know about -- but which you know to be compatible with one of the built-in drivers. This may be the case for a brand new device or for one using a custom VID/PID pair.

UsbSerialProber is a class to help you find and instantiate compatible UsbSerialDrivers from the tree of connected UsbDevices. Normally, you will use the default prober returned by UsbSerialProber.getDefaultProber(), which uses the built-in list of well-known VIDs and PIDs that are supported by our drivers.

To use your own set of rules, create and use a custom prober:

// Probe for our custom CDC devices, which use VID 0x1234
// and PIDS 0x0001 and 0x0002.
ProbeTable customTable = new ProbeTable();
customTable.addProduct(0x1234, 0x0001, CdcAcmSerialDriver.class);
customTable.addProduct(0x1234, 0x0002, CdcAcmSerialDriver.class);

UsbSerialProber prober = new UsbSerialProber(customTable);
List<UsbSerialDriver> drivers = prober.findAllDrivers(usbManager);
// ...

Of course, nothing requires you to use UsbSerialProber at all: you can instantiate driver classes directly if you know what you're doing; just supply a compatible UsbDevice.

Compatible Devices

Author, License, and Copyright

usb-serial-for-android is written and maintained by mike wakerly.

This library is licensed under LGPL Version 2.1. Please see LICENSE.txt for the complete license.

Copyright 2011-2012, Google Inc. All Rights Reserved.

Portions of this library are based on libftdi (http://www.intra2net.com/en/developer/libftdi). Please see FtdiSerialDriver.java for more information.

Help & Discussion

For common problems, see the Troubleshooting wiki page.

For other help and discussion, please join our Google Group, usb-serial-for-android.

Are you using the library? Let us know on the group and we'll add your project to ProjectsUsingUsbSerialForAndroid.

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