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Blinky example for mbed OS 5.0

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Getting started example for Mbed OS

This guide reviews the steps required to get Blinky with the addition of dynamic OS statistics working on an Mbed OS platform. (Note: To see a rendered example you can import into the Arm Online Compiler, please see our quick start.)

Please install Mbed CLI.

Import the example application

From the command-line, import the example:

mbed import mbed-os-example-blinky
cd mbed-os-example-blinky

Now compile

Invoke mbed compile, and specify the name of your platform and your favorite toolchain (GCC_ARM, ARM, IAR). For example, for the Arm Compiler:

mbed compile -m K64F -t ARM

Your PC may take a few minutes to compile your code. At the end, you see the following result:


Image: ./BUILD/K64F/GCC_ARM/mbed-os-example-blinky.bin

Program your board

  1. Connect your Mbed device to the computer over USB.
  2. Copy the binary file to the Mbed device.
  3. Press the reset button to start the program.

The LED on your platform turns on and off. The main thread will additionally take a snapshot of the device’s runtime statistics and display it over serial to your PC. The snapshot includes:

  • System Information:
  • CPU Statistics
    • Percentage of runtime that the device has spent awake versus in sleep
  • Heap Statistics
    • Current heap size
    • Max heap size which refers to the largest the heap has grown to
  • Thread Statistics
    • Provides information on all running threads in the OS including
      • Thread ID
      • Thread Name
      • Thread State
      • Thread Priority
      • Thread Stack Size
      • Thread Stack Space

Compiler Version

Compiler Version Layout
ARM PVVbbbb (P = Major; VV = Minor; bbbb = build number)
GCC VVRRPP (VV = Version; RR = Revision; PP = Patch)
IAR VRRRPPP (V = Version; RRR = Revision; PPP = Patch)

CPUID Register Information

Bit Field Field Description Values
[31:24] Implementer 0x41 = ARM
[23:20] Variant Major revision 0x0 = Revision 0
[19:16] Architecture 0xC = Baseline Architecture
0xF = Constant (Mainline Architecture)
[15:4] Part Number 0xC20 = Cortex-M0
0xC60 = Cortex-M0+
0xC23 = Cortex-M3
0xC24 = Cortex-M4
0xC27 = Cortex-M7
0xD20 = Cortex-M23
0xD21 = Cortex-M33
[3:0] Revision Minor revision: 0x1 = Patch 1

You can view individual examples and additional API information of the statistics collection tools at the bottom of the page in the related links section.


To view the serial output you can use any terminal client of your choosing such as PuTTY or CoolTerm. Unless otherwise specified, printf defaults to a baud rate of 9600 on Mbed OS.

You can find more information on the Mbed OS configuration tools and serial communication in Mbed OS in the related related links section.

The output should contain the following block transmitted at the blinking LED frequency (actual values may vary depending on your target, build profile, and toolchain):

=============================== SYSTEM INFO  ================================
Mbed OS Version: 999999
CPU ID: 0x410fc241
Compiler ID: 2
Compiler Version: 60300
RAM0: Start 0x20000000 Size: 0x30000
RAM1: Start 0x1fff0000 Size: 0x10000
ROM0: Start 0x0 Size: 0x100000
================= CPU STATS =================
Idle: 98% Usage: 2%
================ HEAP STATS =================
Current heap: 1096
Max heap size: 1096
================ THREAD STATS ===============
ID: 0x20001eac
Name: main_thread
State: 2
Priority: 24
Stack Size: 4096
Stack Space: 3296

ID: 0x20000f5c
Name: idle_thread
State: 1
Priority: 1
Stack Size: 512
Stack Space: 352

ID: 0x20000f18
Name: timer_thread
State: 3
Priority: 40
Stack Size: 768
Stack Space: 664


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

Related Links

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.