The USB OTG (On the Go) technology has made it possible to connect the external USB devices such as keyboard, mice, memory sticks, speakers etc., to your Android device directly. All you have to do is connect the micro-USB end of the OTG cable to you Android device and the attach the USB device to the other end of the cable. Your Android device would automatically recognize the attached device and you can use them right away. Some of the Android devices come with USB OTG cable inside the package box, but if you do not have one, then you can buy a simple OTG cable from any mobile store.
But the problem is that some of the Android devices do not have the OTG Host support enabled by default. Some of the manufacturers disable the OTG support in the smartphones because they think that OTG should be enabled only in large screen tablets. In any case, you can use the free USB Host Check app to find whether the OTG Host support is enabled and if it is disabled, it can even try to enable the support on a rooted Android device. If your Android device is not rooted, then you can try Kingo Root to root your device.
As you launch the USB Host Check app, it looks for the contents of three XML files (android.hardware.usb.host.xml, handheld_core_hardware.xml and tablet_core_hardware.xml). If these files do not exist or do not have OTG Host enabled inside them, then USB Host Check shows that your device does not have OTG Host support. You can tap on the Fix button to attempt to fix these files if you have a rooted Android device. Using your superuser app (usually SuperSu), you have to give the root permissions to the USB Host Check app.
If it is not able to fix the support, then it will show one or more red crosses. If it is able to fix the USB Host support, then you would see two green check-marks showing the files it has fixed. In the latter case, you will have to restart your Android device for the changes to take effect.
Conclusion: The USB Host Check app can help you fix the USB OTG Host support in your Android device. It can check to see whether the OTG Host support is enabled in your Android device and if your device is rooted, it can also attempt to fix the problems and enable the OTG Host support.
You can get the USB Host Check app for Android from https://play.google.com/store/apps/details?id=org.tauruslabs.usbhostcheck.