[英]libusb_open returns LIBUSB_ERROR_ACCESS?
I am using libusb in my android app using jni. 我在使用jni的android应用程序中使用libusb。 I am able to find the device using libusb. 我可以使用libusb找到该设备。 but not able to open it. 但无法打开它。
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <libusb.h>
#include <jni.h>
#define MY_VENDOR_ID 0xXXXX
#define MY_PRODUCT_ID 0xXXXX
int is_usbdevblock( libusb_device *dev )
{
struct libusb_device_descriptor desc;
int r = libusb_get_device_descriptor( dev, &desc );
if( desc.idVendor == MY_VENDOR_ID && desc.idProduct == MY_PRODUCT_ID ){
return 1;
}
return 0;
}
char* mymethod()
{
libusb_device **list;
libusb_device *found = NULL;
libusb_context *ctx = NULL;
int attached = 0;
if(libusb_init(&ctx)!=0)
return "libusb init failed";
libusb_set_debug(ctx,3);
ssize_t cnt = libusb_get_device_list(ctx, &list);
ssize_t i = 0;
int err = 0;
if (cnt < 0)
return "No usb device on system";
for(i = 0; i < cnt; i++){
libusb_device *device = list[i];
if( is_usbdevblock(device) ){
found = device;
break;
}
}
if(found){
libusb_device_handle *handle;
err = libusb_open(found, &handle);
if (err)
return "Open error";
return "Device Opened";
}
return "Device not found";
}
JNIEXPORT jstring JNICALL Java_com_example_test_Test_TestOpen(JNIEnv* env, jobject obj)
{
return mymethod();
}
include $(CLEAR_VARS)
LOCAL_MODULE := libusb-1.0
LOCAL_SRC_FILES := libusb-1.0.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := TestExP
LOCAL_SRC_FILES := TestExP.c
LOCAL_SHARED_LIBRARIES += usb-1.0
include $(BUILD_SHARED_LIBRARY)
in my activity class I do following... 在我的活动课程中,我确实遵循...
static{
System.loadLibrary("usb-1.0");
System.loadLibrary("TestExP");
}
public native String TestOpen();
Everything runs fine. 一切运行正常。 when i run this program it returns -3 libusb error code which says " LIBUSB_ERROR_ACCESS " What I am doing wrong. 当我运行该程序时,它返回-3 libusb错误代码,提示“ LIBUSB_ERROR_ACCESS ”,这是我做错了。 Some say give permisions to the usb device. 有人说给USB设备带来麻烦。 I can open the device using Android USB-APIs and make a connection to device. 我可以使用Android USB-API打开设备并建立与设备的连接。 But I want to do that with libusb-1.0. 但是我想用libusb-1.0做到这一点。
Find your device and remember its VID and PID: 找到您的设备并记住其VID和PID:
lsusb
Create rules file: 创建规则文件:
sudo gedit /etc/udev/rules.d/99-my-android-device.rules
Enter next strings to file, fill 03eb
and 204f
with your VID and PID: 输入下一个要归档的字符串,用您的VID和PID填充03eb
和204f
:
ACTION!="add|change", GOTO="my_android_device_rules_end"
SUBSYSTEM!="usb|tty|hidraw", GOTO="my_android_device_rules_end"
ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="204f", MODE="664", GROUP="plugdev"
LABEL="my_android_device_rules_end"
Add yourself to group plugdev
: 将自己添加到plugdev
组:
usermod -aG plugdev $USER
Relogin or restart. 重新登录或重新启动。
Also you could be interested in similar issue . 您也可能对类似问题感兴趣。
将您的用户添加到“ root”组,这将使您可以访问所有USB设备和输入。
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