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Blinky example for Mbed OS 6.0

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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 tools, Arm Mbed CLI 1 and Mbed CLI 2.

(Note: To see a rendered example you can import into the Arm Online Compiler, please see our import quick start.)

Mbed OS build tools

Mbed CLI 2

Starting with version 6.5, Mbed OS uses Mbed CLI 2. It uses Ninja as a build system, and CMake to generate the build environment and manage the build process in a compiler-independent manner. If you are working with Mbed OS version prior to 6.5 then check the section Mbed CLI 1.
1. Install Mbed CLI 2.
1. From the command-line, import the example: mbed-tools import mbed-os-example-blinky
1. Change the current directory to where the project was imported.

Mbed CLI 1

  1. Install Mbed CLI 1.
  2. From the command-line, import the example: mbed import mbed-os-example-blinky
  3. Change the current directory to where the project was imported.

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.

Note: This example requires a target with RTOS support, i.e. one with rtos declared in supported_application_profiles in targets/targets.json in mbed-os. For non-RTOS targets (usually with small memory sizes), please use mbed-os-example-blinky-baremetal instead.

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:

    • Mbed CLI 2

    bash $ mbed-tools compile -m <TARGET> -t <TOOLCHAIN> --flash

    • Mbed CLI 1

    bash $ mbed compile -m <TARGET> -t <TOOLCHAIN> --flash

Your PC may take a few minutes to compile your code.

The binary is located at: * Mbed CLI 2 - ./cmake_build/<TARGET>/develop/<TOOLCHAIN>/mbed-os-example-blinky.bin * Mbed CLI 1 - ./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.

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.