libusb_open_device_with_vid_pid function 返回 0 即使我将 USB 设备连接到 android 手机

Question

I am new to android platform and libusb. I developed an android application which uses libusb in NDK. When I am connecting Pendrive into my android device libusb_open_device_with_vid_pid function returns 0(No device found) . I gave full permission to USB. But still, I am not getting PID and VID of the USB device.

I am execuing libusb_init(NULL) before executing libusb_open_device_with_vid_pid function. I am getting 0 as return value for libusb_init. So there is no issue with libusb initialization.

I have another app that uses android host API. I can view PID and VID of the USB device. But I am unable to view it while i am using libusb.

I am using Samsung S20G android device, libusb version - 1.0.23, Android studio - 4.0.

Does anyone have an idea about this?

Answer 1

Have you tried executing your application as root? In Linux, when you connect a device to the system it'll create a file (in the location /dev). libusb need to access this file which usually requires root permission.

Answer 2

Thank you for your information.

I executed my application as root only. But I didn't get VID and PID. After that I have changed the libusb version and Now I got the VID and PID, data as well.