A V-USB is a very powerful and useful software which is used for implementation of low-speed USB device for all popular AVR controllers by Atmel. It adds USB functionality for almost any AVR, particularly for those without hardware USB functionality. With this, it’s possible to make a very low-cost standalone Arduino with USB port and without having to use an FTDI chip as FTDI chips are really costly when compared to V-USB and it’s hardware counterpart. USB is used mainly for programming the controller and hence it requires a USB based boot loader which is provided by an open-source program named USnoobie.
Another advantage is to use the USB for the serial communication as using a RS232 ic along with a USB to serial cable can increase the cost and as well as it’s unreliable. A special language named HID was used to program. HID stands for Human Interface Device which is a USB class designed primarily for keyboard, mice, joystick, and similar human interface devices. The nice thing about HID is that it’s supported on all operating systems. Overall, the project is brilliant as it provides a low cost alternative to various aspects, as well as it’s compatible with majority of AVR.