The Universal Serial Bus (USB) interface has become extremely popular, due to its simplicity for end user applications (Plug and Play without restart). For developers, however, USB implementation into end systems has been more complicated compared to e.g. RS232. In addition there is a need for device drivers as software support on the PC side. Because of this, RS232 based communication is still very popular among end systems manufacturers. This interface is well established and has good operating system support, but recently the physical RS232 port has been removed from the standard PC interface, giving ground to USB ports. Implementation of USB into external devices can be done in two ways:
1. By using a microcontroller with hardware implemented USB interface. It is necessary to know how USB works and write firmware into the microcontroller accordingly. Additionally, it is necessary to create a driver on the computer side, unless if the operating system includes standard USB classes. The main disadvantage is the lack of availability of this kind of microcontrollers and their high price compared to simple “RS232” microcontrollers.
