This application enables user to send commands to USC-16 servo controller and other devices using CH340 USB to serial chip. Plug in the device using USB OTG cable and the application will start automatically. Set position and speed using seekbars. Position range is 500-2500 ms. Speed is inversely proportional to time, time can be set from 100 ms to 1000 ms. Your Android device must have USB OTG feature and must be able to power the slave device.
For Samsung Galaxy S3 Neo (GT-I9301I) you can turn on power to the slave device using "Power to USB" feature.
The app uses CH34xUARTDriver which can be downloaded here: