Skip to content
This is the mbed Client example application for mbed OS.
C++ C Shell
Branch: master
Clone or download
Pull request Compare This branch is 1 commit ahead, 66 commits behind ARMmbed:master.
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.

Getting started with Mbed Client on Mbed OS

This is the Mbed Client example for Mbed OS. It demonstrates how to register a device with Mbed Device Connector, how to read and write values, and how to deregister. If you are unfamiliar with Mbed Device Connector, we recommend that you read the introduction to the data model first.

Table of Contents

  1. Required software.
  2. Application setup.
  3. Ethernet.
  4. Mesh.
  5. WiFi.
  6. Building the example.
  7. Monitoring the application.
  8. Testing the application.
  9. Known issues.
  10. Troubleshooting.

Required software

The application:

  • Connects to network with WiFi, Ethernet, 6LoWPAN ND or Thread connection.
  • Registers with Mbed Device Connector.
  • Gives Mbed Device Connector access to its resources (read and write).
  • Records the number of clicks on the device’s button and sends the number to Mbed Device Connector.
  • Lets you control the blink pattern of the LED on the device (through Mbed Device Connector).

Application setup

To configure the example application:

  1. Select network and board
  2. Set the client credentials.
  3. Set up an IP address. This step is optional.
  4. Change the socket type. This step is optional.

Select network and board

This example supports following hardware-network combinations:


Supported boards

  • K64F
  • UBLOX_EVK_ODIN_W2 (use the supplied configs/eth_v4.json)

For running the example application using Ethernet, you need:

  • An Ethernet cable.
  • An Ethernet connection to the internet.


There are example settings under the configs directory, which provide the easiest way to start with the applications. The mbed-mesh-api defines the defaults settings for applications. The most relevant parameters are described in more detail in the following sections.

Supported boards

First, you need to select the RF driver to be used by the 6LoWPAN/Thread stack.

This example supports these shields:

To select the radio shield make sure that the mbed_app.json file points to the correct radio driver type:

    "mesh_radio_type": {
            "help": "options are ATMEL, MCR20, SPIRIT1",
            "value": "ATMEL"

Then you need to enable ARM IPv6/6LoWPAN stack. Edit the mbed_app.json file to add NANOSTACK feature with the particular configuration of the stack:

"target.features_add": ["NANOSTACK", "COMMON_PAL"],
"nanostack.configuration": "lowpan_router", 

If your connection type is MESH_THREAD then you may want to use the THREAD_ROUTER configuration:

"target.features_add": ["NANOSTACK", "COMMON_PAL"],
"nanostack.configuration": "thread_router", 

Since 6LoWPAN ND and Thread use IPv6 for connectivity, you need to verify first that you have a working IPv6 connection. To do that, ping the Connector IPv6 address 2607:f0d0:2601:52::20 from your network.

Compile configuration for Spirit1

Note: In case you want to use the STM Spirit1 Sub-1 GHz RF expansion board (X-NUCLEO-IDS01A4), you also need to configure its MAC address in the mbed_app.json file, for example:

    "target_overrides": {
        "*": {
            "spirit1.mac-address": "{0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7}"

Channel settings

The default 2.4GHz channel settings are already defined by the mbed-mesh-api to match the Border Router settings. The application can override these settings by adding them to the .json file. For example:

    "target_overrides": {
        "*": {
            "mbed-mesh-api.6lowpan-nd-channel-page": 0,
            "mbed-mesh-api.6lowpan-nd-channel": 12,
            "mbed-mesh-api.thread-config-channel-page": 0,
            "mbed-mesh-api.thread-config-channel": 22

For sub-GHz shields (Spirit1 or AT86RF212B) use the following overrides, 6LoWPAN ND only:

"mbed-mesh-api.6lowpan-nd-channel-page": 2,
"mbed-mesh-api.6lowpan-nd-channel": 1,
"mbed-mesh-api.6lowpan-nd-channel-mask": "(1<<1)"

For more information about the radio shields, see the related documentation.

Supported combinations of board and shields

See Mesh-minimal's Notes on different hardware for known combinations of development boards and RF shields that have been tested with mesh networking stack.

Border router

You can configure and build the nanostack-border-router for the 6LoWPAN ND or Thread mode.

Thread-specific settings

With Thread, you can change the operating mode of the client from the default router mode to a sleepy end device by adding the following override to the mbed_app.json file:

    "mbed-mesh-api.thread-device-type": "MESH_DEVICE_TYPE_THREAD_SLEEPY_END_DEVICE"

The corresponding Nanostack configuration option is:

    "nanostack.configuration": "thread_end_device"


Supported boards

To run this application using ESP8266 WiFi Interface, you need:

  1. An ESP8266 WiFi module.
  2. Updated Espressif Firmware.
  3. Mount the WiFi module onto K64F Grove Shield v2.
  4. Attach the shield on your board.
  5. In the mbed_app.json file, change:
    "network-interface": {
        "value": "WIFI_ESP8266"

Provide your WiFi SSID and password here and leave \" in the beginning and end of your SSID and password (as shown in the example below). Otherwise, the example cannot pick up the SSID and password in correct format.

    "wifi-ssid": {
        "help": "WiFi SSID",
        "value": "\"SSID\""
    "wifi-password": {
        "help": "WiFi Password",
        "value": "\"Password\""

Note: Some devices do not support the Grove Shield or use the primary UART for USB communication. On such devices, modify the mbed_app.json to use the serial pins connected to the ESP8266.

For example, NUCLEO_F401RE requires a different serial connection:

    "wifi-tx": {
        "help": "TX pin for serial connection to external device",
        "value": "PA_11"
    "wifi-rx": {
        "help": "RX pin for serial connection to external device",
        "value": "PA_12"

Compile configuration for ODIN WiFi

To compile ODIN WiFi configuration, you need to tell mbed NOT to compile mesh files for example. To do that, set up a .mbedignore file. An example file is available in the configs folder.

This should resolve the issue:

cp configs/wifi_odin_v4.json mbed_app.json
<use your favourite editor to modify mbed_app.json for WiFi details>
cp configs/mesh-mbedignore ./.mbedignore 

Compile configuration for STM X-NUCLEO-IDW0XX1 WiFi expansion boards

Currently, two STM WiFi expansion boards are available:

  • X-NUCLEO-IDW01M1, which is the Morpho form-factor board, and
  • X-NUCLEO-IDW04A1, which is the Arduino form-factor board.

The label is clearly printed on the PCB.

To compile STM X-NUCLEO WiFi configuration, you need to tell mbed NOT to compile mesh files for example. To do that, set up a .mbedignore file. Example files are available in the configs folder.

This should resolve the issue (example for X-NUCLEO-IDW01M1):

cp configs/wifi_idw01m1_v4.json mbed_app.json
<use your favourite editor to modify mbed_app.json for WiFi details>
cp configs/mesh-mbedignore ./.mbedignore 

If you have issues with the X-NUCLEO-IDW04A1 board, please double-check that macro IDW04A1_WIFI_HW_BUG_WA has been added to the macros section of the mbed_app.json file.

Compile configuration for REALTEK_RTL8195AM (aka Realtek Ameba) board

Use the supplied configs/wifi_rtw_v4.json file as the basis.

cp configs/wifi_rtw_v4.json mbed_app.json
<use your favourite editor to modify mbed_app.json for WiFi SSID/Password>
mbed compile -m REALTEK_RTL8195AM -t <TOOLCHAIN>

Non listed board support

Apart from the listed configurations, this example can work on other Mbed OS supported hardware boards which support any of the given network interface including Ethernet, WiFi, Mesh (6LoWPAN) or Thread, provided the configuration fulfills condition that the target hardware has TLS entropy implemented for it. On devices where hardware entropy is not present, TLS is disabled by default. This would result in compile time failures or linking failures.

To learn why entropy is required, read the TLS Porting guide.

Also, the complete example configuration of Mbed Client, the selected network interface and Mbed OS components must fit into hardware's given memory size (Flash size and RAM size).

Note: On non-K64F boards, there is no unregistration functionality and button presses are simulated through timer ticks incrementing every 15 seconds.

Note: To see how different targets are built please see the supplied script.

Client credentials

To register the application with the Mbed Device Connector service, you need to create and set the client side certificate.

  1. Go to Mbed Device Connector and log in with your Mbed account.
  2. On Mbed Device Connector, go to My Devices > Security credentials and click the Get my device security credentials to get new credentials for your device.
  3. Replace the contents in the security.h file of this project's folder with the content copied above.

IP address setup

This example uses IPv4 to communicate with the Mbed Device Connector Server except for 6LoWPAN ND and Thread. However, you can easily change it to IPv6 by changing the mbed_app.json you make:

    "target_overrides": {
        "*": {
            "target.features_add": ["LWIP", "NANOSTACK", "COMMON_PAL"],
            "lwip.ipv4-enabled": false,
            "lwip.ipv6-enabled": true,
            "mbed-trace.enable": 0

by modifying the ipv4-enabled or ipv6-enabled to true/false. Only one should be true.

The example program should automatically get an IP address from the router when connected over Ethernet or WiFi.

If your network does not have DHCP enabled, you have to manually assign a static IP address to the board. We recommend having DHCP enabled to make everything run smoothly.

Changing the socket type

Your device can connect to Mbed Device Connector via UDP or TCP binding mode. The default and only allowed value is UDP for Thread and 6LoWPAN. TCP is the default for other connections. The binding mode cannot be changed in 6LoWPAN ND or Thread mode.

To change the binding mode:

  1. In the simpleclient.h file, find the parameter SOCKET_MODE. The default is M2MInterface::UDP for mesh and M2MInterface::TCP for others.
  2. To switch to UDP, change it to M2MInterface::UDP.
  3. Rebuild and flash the application.

Tip: The instructions in this document remain the same, irrespective of the socket mode you select.

Possible socket types per connection:

Network interface UDP TCP
Ethernet (IPv4) X X
Ethernet (IPv6) X
Wifi (IPv4) X X
Wifi (IPv6) - Not supported
6LoWPAN/Thread (IPv6) X

Building the example

To build the example using Mbed CLI:

  1. Open a command line tool and navigate to the project’s directory.

  2. Import this example:

    mbed import mbed-os-example-client
  3. To build the application, select the hardware board and build the toolchain using the command:

    (Specify the config file in the build command, for example for 6LoWPAN)

    mbed compile -m K64F -t GCC_ARM -c --app-config configs/6lowpan_Atmel_RF.json

    If you are using either of the following configurations remember to copy .mbedignore as well:

    cp configs/eth-wifi-mbedignore ./.mbedignore 

    mbed CLI builds a binary file under the project’s BUILD/ directory.

  4. Plug the Ethernet cable into the board if you are using Ethernet mode.

  5. If you are using 6LoWPAN ND or Thread mode, connect and power on the Border Router first.

  6. Plug the micro-USB cable into the OpenSDA port. The board is listed as a mass-storage device.

  7. Drag the binary BUILD/K64F/GCC_ARM/mbed-os-example-client.bin to the board to flash the application.

  8. The board is automatically programmed with the new binary. A flashing LED on it indicates that it is still working. When the LED stops blinking, the board is ready to work.

  9. Press the Reset button on the board to run the program.

  10. For verification, continue to the Monitoring the application chapter.

To build the example using the Online IDE:

Import this repository in the Online IDE and continue from step 3 onwards.

Monitoring the application

The application prints debug messages over the serial port, so you can monitor its activity with a serial port monitor. The application uses baud rate 115200.

Note: Instructions to set this up are located here.

After connecting, you should see messages about connecting to Mbed Device Connector:

Starting mbed Client example
[EasyConnect] IPv4 mode
[EasyConnect] Using Ethernet
[EasyConnect] Connected to Network successfully
[EasyConnect] IP address
[EasyConnect] MAC address 5c:cf:7f:86:de:bf


Connecting to coap://

Registered object succesfully!

Note: Device name is the endpoint name you will need later on when testing the application.

When you press the SW2 button on your board you should see messages about the value changes:

handle_button_click, new value of counter is 1

Testing the application

  1. Flash the application.
  2. Verify that the registration succeeded. You should see Registered object successfully! printed to the serial port.
  3. On Mbed Device Connector, go to My devices > Connected devices. Your device should be listed here.
  4. Press the SW2 button on the device a number of times (make a note of how many times you did that).
  5. Go to Device Connector > API Console.
  6. Click the Endpoint directory lookups drop down menu.
  7. In the menu, click GET next to Endpoint's resource representation. Select your endpoint and resource-path. For example, the endpoint is the identifier of your endpoint that can be found in the security.h file as MBED_ENDPOINT_NAME. Select 3200/0/5501as a resource path and click TEST API.
  8. The number of times you pressed SW2 is shown.
  9. Press the SW3 button to unregister from Mbed Device Connector. You should see Unregistered Object Successfully printed to the serial port and the LED starts blinking. This will also stop your application. Press the Reset button to run the program again.

Note: On non-K64F boards, there is no unregistration functionality and button presses are simulated through timer ticks incrementing every 15 seconds.

SW2 pressed five times, as shown by the API Console

Tip: If you get an error, for example Server Response: 410 (Gone), clear your browser's cache, log out, and log back in.

Note: Only GET methods can be executed through Device Connector > API Console. For other methods, check the mbed Device Connector Quick Start.

Application resources

The application exposes three resources:

  1. 3200/0/5501. Number of presses of SW2 (GET).
  2. 3201/0/5850. Blink function, blinks LED1 when executed (POST).
  3. 3201/0/5853. Blink pattern, used by the blink function to determine how to blink. In the format of 1000:500:1000:500:1000:500 (PUT).

To learn how to get notifications when resource 1 changes, or how to use resources 2 and 3, read the Mbed Device Connector Quick Start.

Known issues

  1. Mutex issue using debug profile, issue #303.
  2. UDP connection fails with on-line compiler (ARM CC 5.06 update 3) #357.

As ARM Compiler 5.06 update 3 has multiple compiler bugs (issue 2 above), we recommend updating to 5.06 update 6.


Realtek RTL8195AM board does not have any LEDs that would be connected to the main MCU. The existing LEDs are all connected to the DAPLINK host processor. So, in order to get the LEDs working one has to connect an external LED, instead. The LED needs to be connected to GPIOB_4 and GND, please see pinout in Realtek RTL8195AM-page.

The board does not have any buttons connected to the main MCU either, so that is why the button is mapped to NC (Not Connected) in the wifi_rtw_v4.json.

Secondly, at least for now, this board is not fully without issues. The following issues have been raised in Mbed OS repository - please follow those for fixes.

  1. ISR overflow issues with this example - Mbed OS #5640.
  2. Compilation issues with on-line compiler - Mbed OS #5626.
  3. Stability issues - Mbed OS #5056.
  4. UVision support not complete - Mbed OS #4651.
  5. DAPLINK in REALTEK-RTL8195AM is a bit old - Mbed OS #5643.

All of these issues are being worked on and fixes will come in, so please follow-up the related items.


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

You can’t perform that action at this time.