Introduction 
Universal Asynchronous Receiver Transmitters (UARTs) are a decades-old technology used at relatively low baud rates for serial data communication in many applications. The Silicon Labs Si890x Monitoring ADC family includes the Si8900, which has a simple Rx/Tx UART interface. The Si8900 does not have dedicated baud rate selection pins, but instead uses an adaptive baud rate detection algorithm to synchronize the baud rate between the Si8900 and the master controller. The Si8900 automatically detects and adapts to the hosts baud rate to a maximum of 520 kbps. This application note explains how the adaptive baud rate detection is implemented and includes proven firmware routines for the users host to establish initial communication.