# Technical Documentation: mik3y/usb-serial-for-android

> ℹ️ **Provenance:** Multi-Tier Ingestion · [CodeWiki Reference](https://codewiki.google/github.com/mik3y/usb-serial-for-android)

### Overview (`README.md`)

[](https://github.com/mik3y/usb-serial-for-android/actions)
[](https://jitpack.io/#mik3y/usb-serial-for-android)
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[](https://codecov.io/gh/mik3y/usb-serial-for-android)

# 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 Mode (OTG)](http://developer.android.com/guide/topics/connectivity/usb/host.html)
available since Android 3.1 and working reliably since Android 4.2.

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 functions](https://github.com/mik3y/usb-serial-for-android/wiki/FAQ#Feature_Matrix) for use with your own protocols.

## Quick Start

**1.** Add library to your project:

Add jitpack.io repository to your root build.gradle:
```gradle
allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}
```

Starting with gradle 6.8 you can alternatively add jitpack.io repository to your settings.gradle:
```gradle
dependencyResolutionManagement {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}
```

If using gradle kotlin  use line
```gradle.kts
        maven(url = "https://jitpack.io")
```

Add library to dependencies
```gradle
dependencies {
    implementation 'com.github.mik3y:usb-serial-for-android:3.11.0'
}
```

**2.** If the app should be notified when a device is attached, add 
[device_filter.xml](https://github.com/mik3y/usb-serial-for-android/blob/master/usbSerialExamples/src/main/res/xml/device_filter.xml) 
to your project's `res/xml/` directory and configure in your `AndroidManifest.xml`.

```xml
<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>
```

**3.** Use it! Example code snippet:

open device:
```java
    // 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) {
        // add UsbManager.requestPermission(driver.getDevice(), ..) handling here
        return;
    }

    UsbSerialPort port = driver.getPorts().get(0); // Most devices have just one port (port 0)
    port.open(connection);
    port.setParameters(115200, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);
```
then use direct read/write
```java
    port.write(request, WRITE_WAIT_MILLIS);
    len = port.read(response, READ_WAIT_MILLIS);
```
or direct write + event driven read:
```java
    usbIoManager = new SerialInputOutputManager(usbSerialPort, this);
    usbIoManager.start();
    ...
    port.write("hello".getBytes(), WRITE_WAIT_MILLIS);
    
@Override
public void onNewData(byte[] data) {
    runOnUiThread(() -> { textView.append(new String(data)); });
}
```
and finally:
```java
    port.close();
```

For a simple example, see
[UsbSerialExamples](https://github.com/mik3y/usb-serial-for-android/blob/master/usbSerialExamples)
folder in this project.

See separate github project [SimpleUsbTerminal](https://github.com/kai-morich/SimpleUsbTerminal) 
for a more complete example with:
* Background service to stay connected while the app is not visible or rotating
* Flow control 

## 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 USB interface types and 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:

```java
// Probe for our custom FTDI device, which use VID 0x1234 and PID 0x0001 and 0x0002.
ProbeTable customTable = new ProbeTable();
customTable.addProduct(0x1234, 0x0001, FtdiSerialDriver.class);
customTable.addProduct(0x1234, 0x0002, FtdiSerialDriver.class);

UsbSerialProber prober = new UsbSerialProber(customTable);
List<UsbSerialDriver> drivers = prober.findAllDrivers(usbManager);
// ...
```
*Note*: as of v3.5.0 this library detects CDC/ACM devices by USB interface types instead of fixed VID+PID,
so custom probers are typically not required any more for CDC/ACM devices.

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

This library supports USB to serial converter chips with specific drivers
* FTDI FT232R, FT232H, FT2232H, FT4232H, FT230X, FT231X, FT234XD
* Prolific PL2303
* Silabs CP2102, CP210*
* Qinheng CH340, CH341A

some other device specific drivers
* GsmModem devices, e.g. for Unisoc based Fibocom GSM modems
* Chrome OS CCD (Closed Case Debugging)

and devices implementing the generic CDC/ACM protocol like
* Qinheng CH343, CH9102
* Microchip MCP2221
* Arduino using ATmega32U4
* Digispark using V-USB software USB
* ...

## Help & Discussion

For common problems, see the [FAQ](https://github.com/mik3y/usb-serial-for-android/wiki/FAQ) wiki page.

Are you using the library? Add your project to 
[ProjectsUsingUsbSerialForAndroid](https://github.com/mik3y/usb-serial-for-android/wiki/Projects-Using-usb-serial-for-android).

---

### Overview (`test/arduino_leonardo_bridge_castrated_cdc/README.md`)

## castrated CDC test (single interface with 3 endpoints)

As mentioned [here](https://arduino.stackexchange.com/a/31695/62145), Arduino functions can be _overwritten_ by copying complete files into the own project. 

This is used to create a castrated CDC device with a single interface containing 3 endpoints. 

The modifications have been done against Arduino 1.8.10, for changes see comments containing `kai`.

---

### Overview (`test/arduino_leonardo_bridge_multi_cdc/README.md`)

## multiple CDC interface test

As mentioned [here](https://arduino.stackexchange.com/a/31695/62145),  Arduino functions can be _overwritten_ by copying complete files into the own project. 

This is used to create a device with 2 CDC interfaces. For simplicity only one of both is functional (configurable in USBDesc.h)

The modifications have been done against Arduino 1.8.10, for changes see comments containing `kai`.

---

### Overview (`test/pi_pico/README.md`)

# `tinyusb_dev_cdc_dual_ports.uf2`

compiled from `C:/Program Files/Raspberry Pi/Pico SDK v1.5.1/pico-sdk/lib/tinyusb/examples/device/cdc_dual_ports`
to `C:/Users/` _user_`/Documents/Pico-v1.5.1/pico-examples/build/usb/device/tinyusb_device_examples/cdc_dual_ports/tinyusb_dev_cdc_dual_ports.uf2`

---

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