AXI UART 16550 standalone driver

This page gives an overview of UART 16550 driver which is available as part of the Xilinx Vivado and SDK distribution.

Table of Contents


The LogiCORE™ IP AXI Universal Asynchronous Receiver Transmitter (UART) 16550 connects to the Advanced
Microcontroller Bus Architecture (AMBA®) AXI and provides the controller interface for asynchronous serial
data transfer. This soft IP core is designed to connect through an AXI4-Lite interface.

Driver Sources

The source code for the driver is included with the Vitis Unified Software Platform installation, as well as being available in the Xilinx Github repository.

Driver NamePath in VitisPath in Github
uartns550<Vitis Install Directory>/data/embedded/XilinxProcessorIPLib/drivers/uartns550

Note: To view the sources for a particular release, use the rel-version tag in github.  For example, for the 2020.1 release, the proper version of the code is:

The driver source code is organized into different folders.  The table below shows the uartns550 driver source organization. 



Provides the API and data structure details


Driver .tcl, .yaml and .mdd file


Example applications that show how to use the driver features


Driver source files, make and cmakelists file

Note: AMD Xilinx embeddedsw build flow has been changed from 2023.2 release to adapt to the new system device tree based flow. For further information, refer to the wiki link Porting embeddedsw components to system device tree (SDT) based flow
The .yaml(in data folder) and CMakeLists.txt(in src folder) files are needed for the System Device Tree based flow. The Driver .tcl and .mdd files are for the older build flow which will be deprecated in future.

Driver Implementation

For a full list of features supported by this IP, please refer


  • AXI4-Lite interface for register access and data transfers
  • Hardware and software register compatible with all
  • standard 16450 and 16550 UARTs
  • Supports default core configuration for 9600 baud, 8 bits data length, 1 stop bit and no parity
  • Implements all standard serial interface protocols
    • 5, 6, 7 or 8 bits per character
    • Odd, Even or no parity detection and generation
    • 1, 1.5 or 2 stop bit detection and generation
    • Internal baud rate generator and separate receiver clock input
    • Modem control functions
    • Prioritized transmit, receive, line status and modem control interrupts
    • False start bit detection and recover
    • Line break detection and generation
    • Internal loopback diagnostic functionality
    • 16 character transmit and receive FIFOs

Known Issues and Limitations


Driver Supported Features

The UART 16550 Standalone driver support the below things.
All Controller Features supported.

Known issues and Limitations

  • None.

Example Applications

Refer to the driver examples directory for various example applications that exercise the different features of the driver. Each application is linked in the table below. The following sections describe the usage and expected output of the various applications.  These example applications can be imported into the Vitis IDE from the Board Support Package  settings tab.

Uartns550 interrupt examplexuartns550_intr_example.cThis example sends and receives data using interrupts
Uartns550 polled examplexuartns550_polled_example.cThis example sends and receives data using polling
Uartns550 hello world examplexuartns550_hello_world_example.cThis example transmits "Hello world" string

Example Application Usage

Uartns550 interrupt example

This example sends and receives data using interrupts

Expected Output

Successfully ran Uartns550 interrupt Example

Uartns550 polled example

This example sends and receives data using polling
Expected Output
Successfully ran Uartns550 polled Example

Uartns550 hello world example

This example transmits "Hello world" string
Expected Output
Successfully ran Uartns550 hello world Example

Example Design Architecture


Change Log


















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