Hardware Implementation of UART and I2C: Design Characteristics and Engineering Trade-offs

Abstract

Universal Asynchronous Receiver/Transmitter (UART) and Inter-Integrated Circuit (I2C) are widely used serial communication interfaces in embedded systems, but their hardware implementation choices are often made without a clear comparison of timing control, control logic, and application boundaries. Based on protocol specifications and existing Field-Programmable Gate Array (FPGA) and System-on-Chip (SoC)- oriented implementation studies, this paper compares UART and I2C from the perspectives of communication mechanism, hardware architecture, timing management, implementation complexity, reliability feedback, and engineering application. The comparison shows that UART has a simpler frame-based structure and lower implementation cost, making it suitable for point-to-point communication, debugging interfaces, and resource-limited systems, while I2C provides stronger bus-level scalability through address recognition, Acknowledge/Not Acknowledge (ACK/NACK) response, and shared Serial Clock Line (SCL) and Serial Data Line (SDA), but requires more complex state-machine control and timing verification. This paper provides a structured reference for selecting between UART and I2C in embedded-system designs involving either simple direct links or multi- peripheral expansion.