Android USB host with HID communication

Front-end time to tinker with a HID hardware, need and Android communication, online search a lap, harvest is not small.

The better articles are:
Android USB host with HID communication

Android service creates USB host communication

Where the code is to be noted in some places, please note:

/*** USB HOST connection HID *@authorIVAN **/ Public classMainactivityextendsActivity {Private Static FinalString TAG = "Usb_host"; PrivateUsbmanager Myusbmanager; PrivateUsbdevice Myusbdevice; PrivateUsbinterface MyInterface; Privateusbdeviceconnection mydeviceconnection; Private Final intVendorID = 8457; //change to your hardware ID here Private Final intProductID = 30264; PrivateTextView Info; PrivateUsbendpoint epout; PrivateUsbendpoint ePIN; @Override Public voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);         Setcontentview (R.layout.main); Info=(TextView) Findviewbyid (r.id.info); //Get UsbmanagerMyusbmanager =(Usbmanager) Getsystemservice (Usb_service);         Enumeratedevice ();         Findinterface ();         Opendevice ();     Assignendpoint (); }     /*** Assign endpoints, in | Out, that is, input and output; Here I use 1 for out end, 0 in, and of course you can judge*/

//usb_endpoint_xfer_bulk
/*
#define USB_ENDPOINT_XFER_CONTROL 0--control transmission
#define USB_ENDPOINT_XFER_ISOC 1--equal-time transmission
#define Usb_endpoint_xfer_bulk 2--Block transfer
#define USB_ENDPOINT_XFER_INT 3--Interrupt transmission
* */

    Private void Assignendpoint () {

if (MyInterface! = null) {// This sentence is easy to error and causes a lot of people to ask in the major forums: Why the error?

the code here is replaced by a bit of your own hardware properties to judge it

for (int i = 0; i < Myinterface.getendpointcount (); i++) {

Usbendpoint EP = Myinterface.getendpoint (i);

if (ep.gettype () = = Usbconstants.usb_endpoint_xfer_int) {
if (ep.getdirection () = = Usbconstants.usb_dir_out) {
Epout = EP;

} else {

ePIN = EP;

}
}
}
}

log.d (TAG, getString (R.string.text)); }     /*** Turn on the device*/    Private voidOpendevice () {if(MyInterface! =NULL) {Usbdeviceconnection conn=NULL; //before open to determine whether there is a connection permission, for connection permissions can be statically assigned, you can also dynamically assign permissions, you can check the relevant data            if(Myusbmanager.haspermission (Myusbdevice)) {conn=Myusbmanager.opendevice (Myusbdevice); }             if(conn = =NULL) {                return; }             if(Conn.claiminterface (MyInterface,true) ) {mydeviceconnection= conn;//to this your Android device is already connected to the HID deviceLOG.D (TAG, "Turn on device Success"); } Else{conn.close (); }        }    }     /*** Find Device Interface*/    Private voidFindinterface () {if(Myusbdevice! =NULL) {log.d (TAG,"Interfacecounts:" +Myusbdevice.getinterfacecount ());  for(inti = 0; I < Myusbdevice.getinterfacecount (); i++) {usbinterface intf=Myusbdevice.getinterface (i); //make some judgments based on the devices in your hand, but this information can be printed when you enumerate to the device .                if(Intf.getinterfaceclass () = = 8 && intf.getinterfacesubclass () = = 6 & amp;& Intf.getinterfaceprotocol () = = 80) {MyInterface=intf; LOG.D (TAG,"Find My Device Interface"); }                 Break; }        }    }     /*** Enumerate Devices*/    Private voidEnumeratedevice () {if(Myusbmanager = =NULL)            return; HashMap<string, usbdevice> devicelist =myusbmanager.getdevicelist (); if(!devicelist.isempty ()) {//devicelist is not emptyStringBuffer SB =NewStringBuffer ();  for(Usbdevice device:deviceList.values ()) {Sb.append (device.tostring ()); Sb.append ("\ n");                Info.settext (SB); //Output Device InformationLOG.D (TAG, "deviceinfo:" + device.getvendorid () + "," +Device.getproductid ()); //Enumerating to Devices                if(Device.getvendorid () = =VendorID&& Device.getproductid () = =ProductID) {Myusbdevice=device; LOG.D (TAG,"Enumerate device Success"); } }} @Override Public BooleanOncreateoptionsmenu (Menu menu) {getmenuinflater (). Inflate (R.menu.main, menu); return true; }}

Get the code for the data:

ncount = Mydeviceconnection.bulktransfer (epin, buffer, buffer.length,                              100);

Note the length of the data read here, which is very important for some hardware, some hardware is small or big immediately crash restart, or always return-1

The length of this data needs to be based on the hardware properties,

One way is to get through int inmax = Epin.getmaxpacketsize ();

Another way is to detect the device's data length through the HID program under Windows;

As for the problem of not reading hardware I think the following methods will not help, or hardware does not support, android4.0 above seems to contain the following file information

Place the Android.hardware.usb.host.xml file under/system/etc/permissions, and the second is to add a sentence to the handheld_core_hardware.xml in the same directory < Feature name= "Android.hardware.usb.host" >

Android USB host with HID communication