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Blinky Mbed OS example

The example project is part of the Arm Mbed OS Official Examples and is the getting started example for Mbed OS. It contains an application that repeatedly blinks an LED on supported Mbed boards.

You can build the project with all supported Mbed OS build tools. However, this example project specifically refers to the command-line interface tool Arm Mbed CLI.
(Note: To see a rendered example you can import into the Arm Online Compiler, please see our import quick start.)

  1. Install Mbed CLI.

  2. Clone this repository on your system, and change the current directory to where the project was cloned:

    bash $ git clone && cd mbed-os-example-blinky

    Alternatively, you can download the example project with Arm Mbed CLI using the import subcommand:

    bash $ mbed import mbed-os-example-blinky && cd mbed-os-example-blinky

Application functionality

The main() function is the single thread in the application. It toggles the state of a digital output connected to an LED on the board.

Building and running

  1. Connect a USB cable between the USB port on the board and the host computer.
  2. Run the following command to build the example project and program the microcontroller flash memory:
    bash $ mbed compile -m <TARGET> -t <TOOLCHAIN> --flash
    The binary is located at ./BUILD/<TARGET>/<TOOLCHAIN>/mbed-os-example-blinky.bin.

Alternatively, you can manually copy the binary to the board, which you mount on the host computer over USB.

Depending on the target, you can build the example project with the GCC_ARM, ARM or IAR toolchain. After installing Arm Mbed CLI, run the command below to determine which toolchain supports your target:

$ mbed compile -S

Expected output

The LED on your target turns on and off every 500 milliseconds.


If you have problems, you can review the documentation for suggestions on what could be wrong and how to fix it.

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License and contributions

The software is provided under Apache-2.0 license. Contributions to this project are accepted under the same license. Please see for more info.

This project contains code from other projects. The original license text is included in those source files. They must comply with our license guide.