Goseeko blog

What is UART?

by Team Goseeko

UART is Universal Asynchronous Receiver Transmitter which has its use mainly in serial communication. It basically does serial to parallel data conversion on the transmitter side. Later on again at the receiver side it converts the received data from serial to parallel. Therefore, it is an interconnection between the processor and the serial communication port.

In conclusion to the figure, shows the connection of UART with the controller and USB interface. The timing settings between the transmitter and receiver in this case are of major concern. In order to maintain synchronisation UART uses special bits at the starting and end of each word.

  • Then UART at the sender end receives the parallel data.
  • Then it converts it to serial data.
  • Similarly at the receiving end UART receives this serial data.
  • Then this serial data is again converted it to parallel.
  • Then the parallel data is sent back to the CPU.

Working of UART

The transmission in UART is asynchronous. The transmitter and receiver do not have any timing synchronization. For synchronization we use these special bits. These bits are Start and Stop bits. The Main function of these bits are

  • Firstly, these bits are attached at the start and end of the data.
  • Also which allows the receiver to identify the actual data.

The data bus transfers the data to the transmitting UART from the controlling device. This received data is in parallel. 

To the data which we received to that we add start, parity and stop bits. The shift register converts the serial data which already contain special bits. At the Rx pin the receiving UART receives this serial data. The special bits tells about the original data. The parity bit defines the integrity of data.

The special builds from the received data are separated and it is again converted back to parallel data. The data bus takes data and sends it back to the receiving end of controller.

Necessary requirement for UART

The requirements for data transmission are written below.

  • Synchronization Bits (Start and Stop bits)
  • Parity Bit
  • Data Bits and
  • Baud Rate

Baud rate is the rate of data transmission. The unit of baud rate is bits per second.


In many areas we see applications of UART as listed below

  • GPS Receivers
  • Bluetooth Modules
  • GSM.
  • GPRS Modems
  • Wireless Communication Systems
  • RFID based applications

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