我正在开发一个应用程序，使用Android的USB主机API通过USB接口将arduino duemilanove板与android 4.1.1智能手机连接。我已经使用windows的USB View应用程序来查找arduino duemelanove板的USB描述符。通过使用这些描述符，我可以在android平台上找到端点和接口。描述符如下：
Device Descriptor:
bcdUSB: 0x0200
bDeviceClass: 0x00
bDeviceSubClass: 0x00
bDeviceProtocol: 0x00
bMaxPacketSize0: 0x08 (8)
idVendor: 0x0403 (Future Technology Devices International Limited)
idProduct: 0x6001
bcdDevice: 0x0600
iManufacturer: 0x01
0x0409: "FTDI"
iProduct: 0x02
0x0409: "FT232R USB UART"
0x0409: "FT232R USB UART"
iSerialNumber: 0x03
0x0409: "A9GJFH5T"
bNumConfigurations: 0x01
Configuration Descriptor:
wTotalLength: 0x0020
bNumInterfaces: 0x01
bConfigurationValue: 0x01
iConfiguration: 0x00
bmAttributes: 0xA0 (Bus Powered Remote Wakeup)
MaxPower: 0x2D (90 Ma)
Interface Descriptor:
bInterfaceNumber: 0x00
bAlternateSetting: 0x00
bNumEndpoints: 0x02
bInterfaceClass: 0xFF
bInterfaceSubClass: 0xFF
bInterfaceProtocol: 0xFF
iInterface: 0x02
0x0409: "FT232R USB UART"
0x0409: "FT232R USB UART"
Endpoint Descriptor:
bEndpointAddress: 0x81
Transfer Type: Bulk
wMaxPacketSize: 0x0040 (64)
bInterval: 0x00
Endpoint Descriptor:
bEndpointAddress: 0x02
Transfer Type: Bulk
wMaxPacketSize: 0x0040 (64)
bInterval: 0x00
应用程序检测到设备并在分配的文本视图中显示所有描述符。但问题是 - 当我尝试使用android的USB主机API的UsbManager类的UsbManager.openDevice(UsbDevice)方法打开设备时，我发现该方法在UsbDeviceConnection变量中返回一个空值
这是实现打开UsbConnection的所有方法的线程
private class SetupThread extends Thread {
public void run() {
String devParam = "";
String intfepParam = "";
// display device descriptor
devParam = ardParam.devinfoRet(arduino);
devDscrptor.setText(devParam);
intf = ardParam.findIntf(arduino);
if (intf != null) {
intfepParam = ardParam.intfPara(intf);
log1.setText("Interface found");
epIn = ardParam.findepIn(intf);
epOut = ardParam.findepOut(intf);
if (epIn != null && epOut != null) {
log2.setText("Both endpoints found");
intfepParam += ardParam.epPara(epIn);
intfepParam += ardParam.epPara(epOut);
intfepDscrptor.setText(intfepParam);
// just checking if Usbdevice arduino is null
if (arduino != null) {
// this is where the problem comes
mConnection = mUsbManager.openDevice(arduino);
conxnInfo.setText("Arduino not null");
}
if (mConnection != null) {
mConnection.claimInterface(intf, false);
conxnInfo.setText("Connection opened");
}
}
else {
if ((epIn == null) && (epOut == null)) {
intfepDscrptor.setText(intfepParam);
log2.setText("Both endpoints null");
}
else if ((epIn == null) && (epOut != null)) {
intfepParam += ardParam.epPara(epOut);
intfepDscrptor.setText(intfepParam);
log2.setText("epIn null");
}
else {
intfepParam += ardParam.epPara(epIn);
intfepDscrptor.setText(intfepParam);
log2.setText("epOut null");
}
}
} else {
log1.setText("Interface is null");
}
}
}
ardParam是ArduinoParams类的对象，ArduinoParams类的代码如下：
package com.example.arduinobasic;
import android.hardware.usb.UsbConstants;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbEndpoint;
import android.hardware.usb.UsbInterface;
public class ArduinoParams {
public String devinfoRet(UsbDevice device) {
String DevInfo = "";
DevInfo += "Device Name:" + device.getDeviceName();
DevInfo += "Device Id:" + device.getDeviceId();
DevInfo += "Product Id:" + device.getProductId();
DevInfo += "Vendor Id:" + device.getProductId();
DevInfo += "Device Class:" + device.getDeviceClass();
DevInfo += "Device Subclass" + device.getDeviceSubclass();
DevInfo += "Device Protocol:" + device.getDeviceProtocol() + "\n";
return DevInfo;
}
public UsbInterface findIntf(UsbDevice device) {
UsbInterface intf = null;
for (int i = 0; i < device.getInterfaceCount(); i++) {
if (device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_VENDOR_SPEC
&& device.getInterface(i).getInterfaceSubclass() == 255
&& device.getInterface(i).getInterfaceProtocol() == 255) {
intf = device.getInterface(i);
}
}
return intf;
}
public UsbEndpoint findepIn(UsbInterface intf) {
UsbEndpoint epin = null;
for (int i = 0; i < intf.getEndpointCount(); i++) {
if ((intf.getEndpoint(i).getDirection() == UsbConstants.USB_DIR_IN)
&& (intf.getEndpoint(i).getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
epin = intf.getEndpoint(i);
}
}
return epin;
}
public UsbEndpoint findepOut(UsbInterface intf) {
UsbEndpoint epout = null;
for (int i = 0; i < intf.getEndpointCount(); i++) {
if ((intf.getEndpoint(i).getDirection() == UsbConstants.USB_DIR_OUT)
&& (intf.getEndpoint(i).getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
epout = intf.getEndpoint(i);
}
}
return epout;
}
public String intfPara(UsbInterface intf) {
String intfPara = "";
intfPara += "Interface id:" + intf.getId();
intfPara += "Interface Class:" + intf.getInterfaceClass();
intfPara += "Interface Subclass:" + intf.getInterfaceSubclass();
intfPara += "Interface Protocol:" + intf.getInterfaceProtocol() + "\n";
return intfPara;
}
public String epPara(UsbEndpoint ep) {
String epPara = "";
epPara += "Endpoint Address:" + ep.getAddress();
epPara += "Endpoint Attributes:" + ep.getAttributes();
epPara += "Endpoint Direction" + ep.getDirection();
epPara += "Endpoint Number:" + ep.getEndpointNumber();
epPara += "Endpoint max pckt size :" + ep.getMaxPacketSize();
epPara += "Endpoint Interval :" + ep.getInterval();
epPara += "Endpoint Type:" + ep.getType() + "\n";
return epPara;
}
}
很抱歉使用了很多if-else语句。我希望有人帮我解决这个问题。提前谢谢。