An embedded converter from RS232 to Universal Serial Bus

Universal Serial Bus (USB) is a new personal computer interconnection protocol, developed to make the connection of peripheral devices to a computer easier and more efficient. It reduces the cost for the end user, improves communication speed and supports simultaneous attachment of multiple devices (up to 127). RS232, on the other hand, was designed for single device connection, but is one of the most used communication protocols. An embedded converter from RS232 to USB is very interesting, since it would allow serial-based devices to experience USB advantages without major changes. This work describes the specification and development of such a converter and it is also a useful guide for implementing other USB devices. The converter specification was based on Engetron UPS' serial communication requirements and its implementation uses a Cypress microcontroller with USB support.