In Android Side:
MainActivity.java
package com.example.androidusbhost;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Iterator;
import android.hardware.usb.UsbConstants;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;
import android.hardware.usb.UsbEndpoint;
import android.hardware.usb.UsbInterface;
import android.hardware.usb.UsbManager;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
public class MainActivity extends Activity {
TextView textInfo;
TextView textSearchedEndpoint;
TextView textDeviceName;
TextView textStatus;
private static final int targetVendorID= 9025;
private static final int targetProductID = 32828;
UsbDevice deviceFound = null;
UsbInterface usbInterfaceFound = null;
UsbEndpoint endpointIn = null;
UsbEndpoint endpointOut = null;
private static final String ACTION_USB_PERMISSION =
"com.android.example.USB_PERMISSION";
PendingIntent mPermissionIntent;
UsbInterface usbInterface;
UsbDeviceConnection usbDeviceConnection;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textStatus = (TextView)findViewById(R.id.textstatus);
textDeviceName = (TextView)findViewById(R.id.textdevicename);
textInfo = (TextView) findViewById(R.id.info);
textSearchedEndpoint = (TextView)findViewById(R.id.searchedendpoint);
//register the broadcast receiver
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
registerReceiver(mUsbDeviceReceiver, new IntentFilter(UsbManager.ACTION_USB_DEVICE_ATTACHED));
registerReceiver(mUsbDeviceReceiver, new IntentFilter(UsbManager.ACTION_USB_DEVICE_DETACHED));
connectUsb();
}
@Override
protected void onDestroy() {
releaseUsb();
unregisterReceiver(mUsbReceiver);
unregisterReceiver(mUsbDeviceReceiver);
super.onDestroy();
}
private void connectUsb(){
Toast.makeText(MainActivity.this,
"connectUsb()",
Toast.LENGTH_LONG).show();
textStatus.setText("connectUsb()");
searchEndPoint();
if(usbInterfaceFound != null){
setupUsbComm();
}
}
private void releaseUsb(){
Toast.makeText(MainActivity.this,
"releaseUsb()",
Toast.LENGTH_LONG).show();
textStatus.setText("releaseUsb()");
if(usbDeviceConnection != null){
if(usbInterface != null){
usbDeviceConnection.releaseInterface(usbInterface);
usbInterface = null;
}
usbDeviceConnection.close();
usbDeviceConnection = null;
}
deviceFound = null;
usbInterfaceFound = null;
endpointIn = null;
endpointOut = null;
}
private void searchEndPoint(){
textInfo.setText("");
textSearchedEndpoint.setText("");
usbInterfaceFound = null;
endpointOut = null;
endpointIn = null;
//Search device for targetVendorID and targetProductID
if(deviceFound == null){
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
while (deviceIterator.hasNext()) {
UsbDevice device = deviceIterator.next();
if(device.getVendorId()==targetVendorID){
if(device.getProductId()==targetProductID){
deviceFound = device;
}
}
}
}
if(deviceFound==null){
Toast.makeText(MainActivity.this,
"device not found",
Toast.LENGTH_LONG).show();
textStatus.setText("device not found");
}else{
String s = deviceFound.toString() + "\n" +
"DeviceID: " + deviceFound.getDeviceId() + "\n" +
"DeviceName: " + deviceFound.getDeviceName() + "\n" +
"DeviceClass: " + deviceFound.getDeviceClass() + "\n" +
"DeviceSubClass: " + deviceFound.getDeviceSubclass() + "\n" +
"VendorID: " + deviceFound.getVendorId() + "\n" +
"ProductID: " + deviceFound.getProductId() + "\n" +
"InterfaceCount: " + deviceFound.getInterfaceCount();
textInfo.setText(s);
//Search for UsbInterface with Endpoint of USB_ENDPOINT_XFER_BULK,
//and direction USB_DIR_OUT and USB_DIR_IN
for(int i=0; i<deviceFound.getInterfaceCount(); i++){
UsbInterface usbif = deviceFound.getInterface(i);
UsbEndpoint tOut = null;
UsbEndpoint tIn = null;
int tEndpointCnt = usbif.getEndpointCount();
if(tEndpointCnt>=2){
for(int j=0; j<tEndpointCnt; j++){
if(usbif.getEndpoint(j).getType() ==
UsbConstants.USB_ENDPOINT_XFER_BULK){
if(usbif.getEndpoint(j).getDirection() ==
UsbConstants.USB_DIR_OUT){
tOut = usbif.getEndpoint(j);
}else if(usbif.getEndpoint(j).getDirection() ==
UsbConstants.USB_DIR_IN){
tIn = usbif.getEndpoint(j);
}
}
}
if(tOut!=null && tIn!=null){
//This interface have both USB_DIR_OUT
//and USB_DIR_IN of USB_ENDPOINT_XFER_BULK
usbInterfaceFound = usbif;
endpointOut = tOut;
endpointIn = tIn;
}
}
}
if(usbInterfaceFound==null){
textSearchedEndpoint.setText("No suitable interface found!");
}else{
textSearchedEndpoint.setText(
"UsbInterface found: " + usbInterfaceFound.toString() + "\n\n" +
"Endpoint OUT: " + endpointOut.toString() + "\n\n" +
"Endpoint IN: " + endpointIn.toString());
}
}
}
private boolean setupUsbComm(){
//for more info, search SET_LINE_CODING and
//SET_CONTROL_LINE_STATE in the document:
//"Universal Serial Bus Class Definitions for Communication Devices"
//at http://adf.ly/dppFt
final int RQSID_SET_LINE_CODING = 0x20;
final int RQSID_SET_CONTROL_LINE_STATE = 0x22;
boolean success = false;
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
Boolean permitToRead = manager.hasPermission(deviceFound);
if(permitToRead){
usbDeviceConnection = manager.openDevice(deviceFound);
if(usbDeviceConnection != null){
usbDeviceConnection.claimInterface(usbInterfaceFound, true);
showRawDescriptors(); //skip it if you no need show RawDescriptors
int usbResult;
usbResult = usbDeviceConnection.controlTransfer(
0x21, //requestType
RQSID_SET_CONTROL_LINE_STATE, //SET_CONTROL_LINE_STATE
0, //value
0, //index
null, //buffer
0, //length
0); //timeout
Toast.makeText(MainActivity.this,
"controlTransfer(SET_CONTROL_LINE_STATE): " + usbResult,
Toast.LENGTH_LONG).show();
//baud rate = 9600
//8 data bit
//1 stop bit
byte[] encodingSetting =
new byte[] {(byte)0x80, 0x25, 0x00, 0x00, 0x00, 0x00, 0x08 };
usbResult = usbDeviceConnection.controlTransfer(
0x21, //requestType
RQSID_SET_LINE_CODING, //SET_LINE_CODING
0, //value
0, //index
encodingSetting, //buffer
7, //length
0); //timeout
Toast.makeText(MainActivity.this,
"controlTransfer(RQSID_SET_LINE_CODING): " + usbResult,
Toast.LENGTH_LONG).show();
byte[] bytesHello =
new byte[] {(byte)'H', 'e', 'l', 'l', 'o', ' ',
'f', 'r', 'o', 'm', ' ',
'A', 'n', 'd', 'r', 'o', 'i', 'd'};
usbResult = usbDeviceConnection.bulkTransfer(
endpointOut,
bytesHello,
bytesHello.length,
0);
Toast.makeText(MainActivity.this,
"bulkTransfer: " + usbResult,
Toast.LENGTH_LONG).show();
}
}else{
manager.requestPermission(deviceFound, mPermissionIntent);
Toast.makeText(MainActivity.this,
"Permission: " + permitToRead,
Toast.LENGTH_LONG).show();
textStatus.setText("Permission: " + permitToRead);
}
return success;
}
private void showRawDescriptors(){
final int STD_USB_REQUEST_GET_DESCRIPTOR = 0x06;
final int LIBUSB_DT_STRING = 0x03;
byte[] buffer = new byte[255];
int indexManufacturer = 14;
int indexProduct = 15;
String stringManufacturer = "";
String stringProduct = "";
byte[] rawDescriptors = usbDeviceConnection.getRawDescriptors();
int lengthManufacturer = usbDeviceConnection.controlTransfer(
UsbConstants.USB_DIR_IN|UsbConstants.USB_TYPE_STANDARD, //requestType
STD_USB_REQUEST_GET_DESCRIPTOR, //request ID for this transaction
(LIBUSB_DT_STRING << 8) | rawDescriptors[indexManufacturer], //value
0, //index
buffer, //buffer
0xFF, //length
0); //timeout
try {
stringManufacturer = new String(buffer, 2, lengthManufacturer-2, "UTF-16LE");
} catch (UnsupportedEncodingException e) {
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_LONG).show();
textStatus.setText(e.toString());
}
int lengthProduct = usbDeviceConnection.controlTransfer(
UsbConstants.USB_DIR_IN|UsbConstants.USB_TYPE_STANDARD,
STD_USB_REQUEST_GET_DESCRIPTOR,
(LIBUSB_DT_STRING << 8) | rawDescriptors[indexProduct],
0,
buffer,
0xFF,
0);
try {
stringProduct = new String(buffer, 2, lengthProduct-2, "UTF-16LE");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
textStatus.setText("Manufacturer: " + stringManufacturer + "\n" +
"Product: " + stringProduct);
}
private final BroadcastReceiver mUsbReceiver =
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (ACTION_USB_PERMISSION.equals(action)) {
Toast.makeText(MainActivity.this,
"ACTION_USB_PERMISSION",
Toast.LENGTH_LONG).show();
textStatus.setText("ACTION_USB_PERMISSION");
synchronized (this) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
if(device != null){
connectUsb();
}
}
else {
Toast.makeText(MainActivity.this,
"permission denied for device " + device,
Toast.LENGTH_LONG).show();
textStatus.setText("permission denied for device " + device);
}
}
}
}
};
private final BroadcastReceiver mUsbDeviceReceiver =
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
deviceFound = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
Toast.makeText(MainActivity.this,
"ACTION_USB_DEVICE_ATTACHED: \n" +
deviceFound.toString(),
Toast.LENGTH_LONG).show();
textStatus.setText("ACTION_USB_DEVICE_ATTACHED: \n" +
deviceFound.toString());
connectUsb();
}else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
Toast.makeText(MainActivity.this,
"ACTION_USB_DEVICE_DETACHED: \n" +
device.toString(),
Toast.LENGTH_LONG).show();
textStatus.setText("ACTION_USB_DEVICE_DETACHED: \n" +
device.toString());
if(device!=null){
if(device == deviceFound){
releaseUsb();
}
}
textInfo.setText("");
}
}
};
}
The setting of usbDeviceConnection.controlTransfer() inside setupUsbComm() is copied from the post: Android USB Host + Arduino: How to communicate without rooting your Android Tablet or Phone
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:autoLink="web"
android:text="http://arteluzevida.blogspot.com/"
android:textStyle="bold" />
<TextView
android:id="@+id/textstatus"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold" />
<TextView
android:id="@+id/textdevicename"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold|italic" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="@+id/info"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/searchedendpoint"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold" />
</LinearLayout>
</ScrollView>
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.androidusbhost"
android:versionCode="1"
android:versionName="1.0" >
<uses-feature android:name="android.hardware.usb.host" />
<uses-sdk
android:minSdkVersion="13"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.androidusbhost.MainActivity"
android:label="@string/app_name"
android:configChanges="keyboard|orientation" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<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" />
<intent-filter>
<action android:name="android.hardware.usb.action.USB_DEVICE_DETACHED" />
</intent-filter>
</activity>
</application>
</manifest>
Download the files.In Arduino Side:
testSerial.ino
#include <Esplora.h>
#include <TFT.h>
#include <SPI.h>
int prevSw1 = HIGH;
int incomingByte = 0;
String charsIn = "";
char printout[20]; //max char to print: 20
void setup() {
EsploraTFT.begin();
EsploraTFT.background(0,0,0);
EsploraTFT.stroke(255,255,255); //preset stroke color
//Setup Serial Port with baud rate of 9600
Serial.begin(9600);
//indicate start
Esplora.writeRGB(255, 255, 255);
delay(250);
Esplora.writeRGB(0, 0, 0);
}
void loop() {
int sw1 = Esplora.readButton(SWITCH_1);
if(sw1 != prevSw1){
if(sw1 == LOW){
Serial.println("Hello from Arduino Esplora");
}
prevSw1 = sw1;
}
while (Serial.available()) {
char charRead = Serial.read();
charsIn.concat(charRead);
}
if(charsIn != ""){
Serial.println("How are you, " + charsIn);
charsIn.toCharArray(printout, 21);
EsploraTFT.background(0,0,0);
EsploraTFT.text(printout, 0, 10);
charsIn = "";
}
}
It's same as the code in my another blog: Serial communication between Arduino Esplora and PC
Step-by-step: Android USB Host Mode programming
