UART (Universal Asynchronous Receiver/Transmitter) is a hardware component designed to handle asynchronous serial communication. Unlike a specific communication protocol, UART is the physical circuit--often integrated into microcontrollers--that acts as the interface between a system's parallel data bus and serial communication lines.
Its primary function is to convert parallel data from the CPU into a serial format for transmission and to reverse this process for reception.
Operating Principles
- Transmission: The UART receives parallel data (typically 8 bits) from the CPU. It frames this data by adding a start bit, an optional parity bit, and stop bits, then transmits the packet bit-by-bit at a specified baud rate.
- Reception: The UART detects the start bit on the serial line, reads the incoming bits, checks for errors using the parity bit, and strips the framing bits. It then reassembles the data into parallel form for the CPU.
UART serves as the fundamental hardware basis for implementing common industrial communication standards, such as RS-232C and RS-485.