Develop Reference

Connecting a Device as a USB Device with STM32 as a USB Host

I want to connect the Android device as a USB Device to an STM32 board which acts as a host device.
My application code for Android looks like:
Android Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.usb_connection">
<uses-feature android:name="android.hardware.usb.accessory" />
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
So when I am trying to get the connected USB device details, the USB Device list is always null :
UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
Map<String,UsbDevice> deviceList = manager.getDeviceList();
Again, I also tried to get the accessory list, the USB accessory list is also null.
UsbAccessory[] accessoryList = manager.getAccessoryList();
Then tried ADB commands to connect the device. I have created a Desktop application in JAVA to run ADB command and its working fine. But when I tried run ADB command from my Android App, it's giving java.io.IOException: Error running exec(). Command: [ ADB, pull , ...] Working Directory: null Environment: null.
STM32 firmware is written in C.
Please help me I am stuck for a long time.

Hey here is my library for Android Accessory mode activation on Stm32(with cube Mx and HAL verified on series f4 and f1) and USB class for bulk communication:
https://github.com/once2go/Stm32-Android-Accessory

What are you trying to do on the STM32 side? You need to first connect to the Android device over USB and determine (on the STM32 side) whether the Android device is in AOA mode (by checking the Vendor and Product ID). If it's not, you need to send some USB requests that will toggle it (I've included the STM32 USBH library call name):
USBH_GetProtocol Version
USBH_SetString 0 manufacturer name
USBH_SetString 1 model name
USBH_SetString 2 description
USBH_SetString 3 version
USBH_SetString 4 URI
USBH_SetString 5 serial number
Start Accessory
You can see that process explained in more detail here:
https://source.android.com/devices/accessories/aoa#attempt-to-start-in-accessory-mode
Once you've done that, you'll disconnect from the USB device (it will reset the connection) and you'll need to redo the enumeration process. This time, the Vendor and Product ID should be that of an AOA device (0x18D1 & 0x2D00/1). Now you can just connect to it and use a fairly standard USBH_CDC communication process, with a few caveats. When you try to find the interface (in your interface init function), your subclass is 0xFF and your protocol is going to be 0x00).
It took me a while to get everything communicating properly, so having a usb logic analyzer is a really handy tool to make sure things are communicating properly.
Here are some other resources for getting the Android device to communicate once the STM32 is doing things correctly.
https://source.android.com/devices/accessories/aoa2
https://developer.android.com/guide/topics/connectivity/usb/accessory.html#manifest

USB Communication between android and PC

Background :I have tried finding help on stackoverflow, android developers, and various other resources on web. This is my last hope.
I am new to communication and starting with implementation of USB. Following are my questions:
1) When I connect my phone to windows PC, which one is host?
Suppose I want to create an application that can send data, am I making my phone host?
2) For the case (Windows PC and Android phone), the other one would be a peripheral or a device? are they same?
3) From android developers website and a windows forum about USB, I understand that there are certain steps that need to be followed, and it's like
- Create an instance of USBManager.
- Create get list of devices
- Choose a device from which you want to establish connection
- Create an interface
- get endpoint from that interface.
- Create instance of DeviceConnections and call bulkTransfer method and send data.
But when I tried above steps, I get device == null.
I don't even know if my understanding for above communication method is correct.
Can someone please help me understand and establish basic communication between a PC and a android phone and send at least "hello world".
Big thank you for even reading such a long question.
Here is code sample of what I have done. here devicelist returns null.
public class MainActivity extends AppCompatActivity {
android.widget.Button usbButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final CustomUSBManager cmanager = new CustomUSBManager();
//1) //Create instance of USB Manager using getSystemService
final UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
//2) //Create a list of devices
HashMap<String,UsbDevice> deviceList = manager.getDeviceList();
Log.d("Devicelist = ", String.valueOf(deviceList.get(0)));
//3) //Get a specific device from the list
//-----------------------------------------------------------------
Here is my manifest file.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.neeraj.usbcommunication1">
<uses-feature android:name="android.hardware.usb.host"></uses-feature>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
final UsbDevice device = deviceList.get(0); //getting first device

This will not work the way you want. The UsbManager.getDeviceList() is meant to be used with Android devices with an USB port (for example a tablet). However, you connect an Android device acting as a device to your PC acting as a host.
If you want to communicate between Android USB device and some USB host you need to use the accessory mode (https://developer.android.com/guide/topics/connectivity/usb/). But this mode requires special driver support on the USB host side (which is your PC).
Also note that getDeviceList() makes no sense in Accessory mode. This is because the connected accessory is a USB host, not a USB device.
Read more about this in this post: Android to PC USB Read/Write
Note that my answer is based on this answer: https://stackoverflow.com/a/14099963/5457878

Enabling Wifi direct in Android 4.0

I have bought a new android 4.0.3 tablet- Micromax Funbook P300 to learn developing android applications.
I started with Wifi Direct, so that the tablet could be used as a remote for robotic platform.
To my disappointment the stock OS doesn't provide this function in the settings menu.
Is it possible to check if we can programatically start wifi direct feature?
If not can someone direct to some tutorials which addresses this?
Thanks.

The Android SDK contains a sample application for using the DirectWiFi mode:
WiFiDirectDemo - Wi-Fi Direct Demo
The used API itself is located in android.net.wifi.p2p

WiFi Direct should be supported by Android 4.0.3 (it has been around since Android API 14, or Android 4.0). It is possible that your tablet does not support WiFi Direct due to a hardware limitation, but I doubt it. You probably aren't seeing it in the settings because there is a custom Android skin running on the tablet that prevents you from seeing it, or maybe the WiFi Direct settings interface wasn't implemented until Android 4.1 or something.
Whatever the case, you can test it easily in the code.
First, put the proper permissions in your manifest.xml
http://developer.android.com/training/connect-devices-wirelessly/wifi-direct.html#permissions
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.nsdchat"
...
<uses-permission
android:required="true"
android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.INTERNET"/>
...
Next, try initializing the Android WiFiP2pManager class to see if it is supported.
http://developer.android.com/reference/android/net/wifi/p2p/WifiP2pManager.html
public void onCreate(Bundle savedInstanceState) {
WifiP2pManager manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
WifiP2pManager.Channel channel = manager.initialize(this, getMainLooper(), null);
}
Where I put null, you could pass a callback to check for failure. If it works, follow the rest of the Wi-Fi Direct guide to create your app.

He's not asking for a coded program example, so much as a way to programatically switch on the technology (ie one line of code). As far as I am aware there is no way to do this. It all has to be done from within your devices settings. While some devices allow Wi-Fi Direct to be switched on, other devices treat it the same as having regular Wi-Fi enabled - have you tried this? And have you checked if the P300 even supports Wi-Fi Direct?

How to detect MTP/PTP device in Honeycomb?

I want to detect the MTP/PTP device when it plugs in the android device. I know there is one method using Intent: android.hardware.usb.action.USB_DEVICE_ATTACHED and then defining meta-data which using resource like <usb-device class="6" subclass="1" protocol="1">, but it doesn't work. The system doesn't send this intent to the registered application.
Thus, does anyone know how to do it?

Have you set the machine to act as USB host by adding into
AndroidManifest.xml:
<uses-feature android:name="android.hardware.usb.host" />

could you please specify what is the device you are using for testing?
It is very likely that your device has no PTP/MTP specific values in class, subclass and protocol for the USB device descriptor and/or interface descriptor.
See this: http://events.linuxfoundation.org/sites/events/files/slides/Media%20Transfer%20Protocol.pdf
Some devices advertise themselves as Mass Storage devices or Vendor Specific.
If that is the case the only way is to try matching the vendor id and product id of the devices you would like to support.
Here is also a list of MTP devices with their vendor id and product id: http://sourceforge.net/p/libmtp/code/ci/HEAD/tree/src/music-players.h.
Hope this helps.

Multicast on Android 2.2

Has anyone gotten Multicast to work on Android 2.2, specifically JmDNS for Bonjour service detection. There are many questions & answers from the Android 1.5->2.0 timeframe, including on stackOverflow, that indicate varying levels of success, and a bug in the bug tracker that indicate it was fixed, and closed, for 2.2 (http://code.google.com/p/android/issues/detail?id=2323) . I've tried the "TuneControl" source code, but that worked on ~1.5 and has not been updated, and does not work for me on 2.2.
So, the questions...
1) Has anyone seen multicast work on 2.2, specifically JmDNS, and specifically for Bonjour service detection?
2) What is necessary in code to make this work?
I'm using the appropriate permissions:
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
I acquire the multicast lock:
WifiManager wifi = (WifiManager)getSystemService( Context.WIFI_SERVICE );
if(wifi != null)
{
MulticastLock mcLock = wifi.createMulticastLock("mylock");
mcLock.acquire();
...
And then try to start jmDNS to look for servers:
mdns = JmDNS.create(addr, HOSTNAME);
jmdns.addServiceListener(TOUCH_ABLE_TYPE, listener);
jmdns.addServiceListener(DACP_TYPE, listener);
...
The listener never sees any services. I've verified using Wireshark that the request packets are sent, and that the server responds, but the response packet are never seen by the socket listener code in the jmDNS library.
So... am I missing something? Is this still a bug? Has ANYONE gotten anything even remotely like this to work???

To (rudely) answer my own question, more information was provided at http://code.google.com/p/android/issues/detail?id=2917#c48 by another person. For posterity, as they say, here is brian.ro...#gmail.com's answer...
"I've spent quite a bit of time
debugging mDNS issues with JmDNS on my
Evo and HTC Hero (CDMA). What I found
is there appears to be a filter in
place in the broadcom wireless driver
on the Evo (and since I'm getting a
similiar reprt from an HTC Desire user
- with the same chipset, presumably that handset as well). The filter, by
default, blocks any non-unicast or
network broadcast traffic, including
multicast. Apparently the theory was
it's a battery saver.
The problem appears to be the
wpa_supplicant on the Evo does not
support removing those filters when
you get a MulticastLock. (Check the
log output right after you get the
lock and you'll see what I mean).
Unfortunately what has happened is the
hardware vendors have fragmented
multicast support.... :("
So... it appears this is a device problem more than a coding problem. D'oh. :( If I get an opportunity to test on another device...

I've been doing a bit of research into this, and I believe it is a problem with Android in general, and fixed in or around Android 2.3.7.
It's a bit too anecdotal, but here's what I tested:
HTC Desire, 2.2, stock: fail
HTC Desire, 2.3.7, CyanogenMod: success
Motorola Milestone, 2.1-update1: fail
HTC Desire S, 2.3.3: fail
Acer Iconia A501, 3.2.1: success
Samsung something, 2.3.3: fail
HTC Legend, 2.2 I think: fail
When I say 'fail', in fact they were all able to send multicast messages to the 'success' devices, but never receive anything back except their own messages - as jldupont describes.
Note that the multicast IM app Kouchat is only available for 2.3.7 onwards, even though it can be made to compile for as far back as 2.1, which gives further credence to this theory.

I think the other reason is your AP does not support.
Other:Computer send/recieve to/from Android
your computer must only use WIFI,Best off all other network