UARTs (Universal Asynchronous Receiver Transmitter)

1. What are UART ICs?

1) ‌Basic Concepts‌

UART ICs (Universal Asynchronous Receiver Transmitter Integrated Circuits) are independent chips or integrated modules dedicated to asynchronous serial communication. Its core function is to perform bidirectional conversion between parallel data (such as from a CPU or microcontroller) and serial data streams.

 

2) ‌Communication Characteristics‌

‌Asynchronous Protocol‌: No need to share a clock signal, relying on a predefined baud rate (Baud Rate) and data frame format (start bit, data bit, check bit, stop bit) to achieve synchronization.

‌Full-duplex Transmission‌: Data is sent and received simultaneously through independent channels of the transmit line (TXD) and the receive line (RXD).

‌Point-to-point Connection‌: Usually used for direct communication between two devices, cross connection (TXD→RXD, RXD→TXD) is required.

 

2. What are the Key Technical Characteristics of UART ICs?

1) ‌Configurable Parameters‌

‌Data Bit Length‌: Supports 5, 6, 7, 8, or 9-bit data frames.

‌Parity Mechanism‌: Optional odd parity, even parity, or no parity.

Stop Bit: 1, 1.5, or 2 stop bits are supported to mark the end of the frame.

Baud Rate: Flexible adaptation to different communication rate requirements through clock division (baud rate = UART clock source / (division coefficient × parameter)).

2) Hardware Buffer: Integrated FIFO buffer (such as 16-byte THR transmit holding register) to improve data transmission efficiency and reduce interrupt frequency.

3) Interrupt Support: Provides interrupt signals such as send completion and receive ready (such as THR empty interrupt) to enhance the real-time response capability of the system.

 

3. What are UART ICs Used for? 

Embedded System Debugging: As a debugging interface between a microcontroller (such as STM32) and a PC or other peripherals, it transmits logs or control instructions.

Industrial Control and Communication: Connects sensors, modems, RS-232/485 converters, and other devices to achieve reliable low-speed data exchange.

Peripheral Expansion: As a bridge chip, it assists the main control processor to communicate with components such as serial memory and display.

 

4. Comparison with Other Serial Protocols

Features	‌UART	‌I²C	‌SPI
Communication Mode	Asynchronous	Synchronous	Synchronous
Number of Signal Lines	2(TXD, RXD)	2(SCL, SDA)	4(SCK, MOSI, MISO, CS)
Topology	Point-to-point	Multiple masters and slaves	One master and multiple slaves
Verification Support	Yes (Optional Parity)	Address/Data Verification	No Built-in Verification
Applicable Scenarios	Long-distance, Simple Equipment	In-board Multi-device Control	High-speed Data Stream Transmission

 

5. What is the Core Value of UART ICs?

UART ICs have become the basic solution for solving serial interconnection between devices in embedded design and industrial communication with the advantages of low cost, low power consumption, and high compatibility, especially for application scenarios with low clock synchronization requirements and simple wiring.