— More and more fieldbus applications require a communication with real-time properties, while still being economically feasible. The fieldbuses LIN and TTP/A take this requirement into account by providing a temporally deterministic communication protocol that uses a common UART (Universal Asynchronous Receiver/Transmitter) as communication interface. Due to the fact, that UARTs originally have not been designed for this kind of application, some problems arise that require increased software and processing effort or reduce the achievable bandwidth. This paper presents a UART module that has been adopted to be used in real-time applications: A synchronization mechanism is provided, which reduces the software complexity and facilitates the periodical synchronization required by the mentioned real time communication protocols. Further the UART is able to initialize actions on occurring events. In this way, a big part of the communication process can be handled autonomously by the UA...