Getting started with mbed Client on mbed OS

This is the mbed Client example for mbed OS (we also have one for Linux). 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.

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).

Required hardware

• FRDM-K64F board.
• 1-2 micro-USB cables.
• mbed 6LoWPAN gateway router for 6LoWPAN ND and Thread.
• mbed 6LoWPAN shield (AT86RF212B/AT86RF233) for 6LoWPAN ND and Thread.
• Ethernet cable and connection to the internet.

Required software

• ARM mbed account.
• mbed-cli - to build the example programs. To learn how to build mbed OS applications with mbed-cli, see the user guide.
• Serial port monitor.

Application setup

To configure the example application, please:

1. Select the connection type.
2. Set the client credentials.
3. Change 6LoWPAN ND & Thread settings.
4. Change Ethernet settings.
5. Change Wi-Fi settings.
6. Set up an IP address. This step is optional.
7. Change the socket type. This step is optional.

Connection type

The application uses Ethernet as the default connection type. To change the connection type, set one of them in mbed_app.json. For example, to enable 6LoWPAN ND mode:

    "network-interface": {
        "help": "options are ETHERNET,WIFI,MESH_LOWPAN_ND,MESH_THREAD.",
        "value": "MESH_LOWPAN_ND"
    }

Client credentials

To register the application to the 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 button to get new credentials for your device.
3. Replace the contents in security.h of this project's directory with content copied above.

6LoWPAN ND and Thread settings

6LoWPAN ND and Thread use IPv6 for connectivity. Therefore, 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.

mbed gateway

To connect the example application in 6LoWPAN ND or Thread mode to Connector, you need to set up an mbed 6LoWPAN gateway router as follows:

1. Use an Ethernet cable to connect the mbed 6LoWPAN gateway router to the internet.

2. Use a micro-USB cable to connect the mbed 6LoWPAN gateway router to your computer. The computer will list the router as removable storage.

3. The firmware for the gateway is located in the GW_Binary folder in the root of this example. Select the binary matching your application bootstrap mode:

   • For the 6LoWPAN ND bootstrap, use gateway6LoWPANDynamic.bin.
   • For the Thread bootstrap, use gatewayThreadDynamic.bin.

   The dynamic binaries use IPv6 autoconfiguration and enable the client to connect to the Connector service. The static binaries create a site-local IPv6 network and packets cannot be routed outside.

4. Copy the gateway binary file to the mbed 6LoWPAN gateway router to flash the device. The device reboots automatically after flashing. If that does not happen, press the Reset button on the board.

You can view debug traces from the gateway with a serial port monitor. The gateway uses baud rate 460800. The gateway IPv6 address is correctly configured when the following trace is visible: Eth bootstrap ready, IP=XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX.

Channel settings

The default 2.4GHz channel settings are already defined by the mbed-mesh-api to match the mbed gateway settings. The application can override these settings by adding them to the mbed_app.json file in the main project directory. 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": 12
        }
    }

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

"mbed-mesh-api.6lowpan-nd-channel-page": 2,
"mbed-mesh-api.6lowpan-nd-channel": 1

For more information about the radio shields, see the related documentation. All the configurable settings can be found in the mbed-os-example-client/mbed-os/features/FEATURE_IPV6/mbed-mesh-api/mbed_lib.json file.

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"

Ethernet settings

For running the example application using Ethernet, you need:

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

Wi-Fi settings

The example application uses ESP8266 WiFi Interface for managing the wireless connectivity. To run this application using WiFi, 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 the K64F board.
5. In the mbed_app.json file, change

    "network-interface": {
        "help": "options are ETHERNET,WIFI,MESH_LOWPAN_ND,MESH_THREAD.",
        "value": "WIFI"
    }

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\""
    }

IP address setup

This example uses IPv4 to communicate with the mbed Device Connector Server except for 6LoWPAN ND and Thread. The example program should automatically get an IPv4 address from the router when connected over Ethernet.

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 socket type

Your device can connect to mbed Device Connector via UDP or TCP binding mode. The default is UDP. 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.
2. To switch to TCP, change it to M2MInterface::TCP.
3. Rebuild and flash the application.

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

Building the example

To build the example application:

1. Clone this repository.
2. Open a command line tool and navigate to the project’s directory.
3. Update mbed-os sources using the mbed update command.
4. Configure the client application.
5. Build the application by selecting the hardware board and build the toolchain using the command mbed compile -m K64F -t GCC_ARM -c -j0. mbed-cli builds a binary file under the project’s .build directory.
6. Plug the Ethernet cable into the board if you are using Ethernet mode.
7. If you are using 6LoWPAN ND or Thread mode, connect and power on the gateway first.
8. Plug the micro-USB cable into the OpenSDA port. The board is listed as a mass-storage device.
9. Drag the binary .build/K64F/GCC_ARM/mbed-os-example-client.bin to the board to flash the application.
10. 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.
11. Press the RESET button on the board to run the program.
12. For verification, continue to the Monitoring the application chapter.

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:

In app_start()
IP address 10.2.15.222
Device name 6868df22-d353-4150-b90a-a878130859d9

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

When you click 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. Enter https://api.connector.mbed.com/endpoints/DEVICE_NAME/3200/0/5501 in the URI field and click TEST API. Replace DEVICE_NAME with your actual endpoint name. The device name can be found in the security.h file, see variable MBED_ENDPOINT_NAME or it can be found from the traces Monitoring the application.
7. The number of times you pressed SW2 is shown.
8. 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.

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).

For information on how to get notifications when resource 1 changes, or how to use resources 2 and 3, take a look at the mbed Device Connector Quick Start.