Understanding the UART/USART Data Frame (Start Bit, Stop Bit, Data Bits, Parity Bit)

The UART and USART communication happens using a data frame. The data frame consists of a start bit, data bits, parity bit and one or two stop bits. The start bit informs the receiving device that the data bits are coming. The data bits are numbers of bits of varying lengths (i.e 8-bits). The parity bit is a check is the data frame contains an error. The stop bits inform the receiving end that the data bits are complete and the data can be processed.