Example program for simple-mbed-client, connecting a device to mbed Device Connector.

Dependencies:   simple-mbed-client

Fork of simple-mbed-client-example by Jan Jongboom

This is an example on how to connect to mbed Device Connector using simple-mbed-client. It can connect over Ethernet, WiFi (using an ESP8266 module or an ODIN board), Thread and 6LoWPAN.

After cloning this repository update `mbed_app.json` to reflect your connectivity method. For docs on configuring connectivity, see easy-connect.

End to end example

For an end-to-end example of using Simple mbed Client to connect devices to mbed Device Connector see Building an internet connected lighting system.

Entropy (or lack thereof)

On all platforms except the K64F and K22F the library is compiled without TLS entropy sources. This means that your code is inherently unsafe and should not be deployed to any production systems. To enable entropy, remove the MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES and MBEDTLS_TEST_NULL_ENTROPY macros from mbed_app.json.


Jan Jongboom

File content as of revision 40:6c039d073c0b:

#include "mbed.h"
#include "security.h"
#include "easy-connect.h"
#include "simple-mbed-client.h"

SimpleMbedClient client;

// Declare peripherals
DigitalOut connectivityLed(LED2);                   // Blinks while connecting, turns solid when connected
DigitalOut augmentedLed(LED1, BUILTIN_LED_OFF);     // LED that can be controlled through Connector
InterruptIn btn(MBED_CONF_APP_BUTTON);              // Button that sends it's count to Connector

Ticker connectivityTicker;

// Callback function when the pattern resource is updated
void patternUpdated(string v) {
    printf("New pattern: %s\n", v.c_str());

// Define resources here. They act as normal variables, but are exposed to the internet...
SimpleResourceInt btn_count = client.define_resource("button/0/clicks", 0, M2MBase::GET_ALLOWED);
SimpleResourceString pattern = client.define_resource("led/0/pattern", "500:500:500:500:500:500:500", &patternUpdated);

void fall() {
    btn_count = btn_count + 1;
    printf("Button count is now %d\r\n", static_cast<int>(btn_count));

void toggleConnectivityLed() {
    connectivityLed = !connectivityLed;

void registered() {

    connectivityLed = BUILTIN_LED_ON;

void play(void* args) {
    connectivityLed = BUILTIN_LED_OFF;

    // Parse the pattern string, and toggle the LED in that pattern
    string s = static_cast<string>(pattern);
    size_t i = 0;
    size_t pos = s.find(':');
    while (pos != string::npos) {
        wait_ms(atoi(s.substr(i, pos - i).c_str()));
        augmentedLed = !augmentedLed;

        i = ++pos;
        pos = s.find(':', pos);

        if (pos == string::npos) {
            wait_ms(atoi(s.substr(i, s.length()).c_str()));
            augmentedLed = !augmentedLed;

    augmentedLed = BUILTIN_LED_OFF;
    connectivityLed = BUILTIN_LED_ON;

int main() {
    // SimpleClient gives us an event queue which we can use, running on a separate thread (see https://docs.mbed.com/docs/mbed-os-handbook/en/5.1/concepts/events/)
    EventQueue* eventQueue = client.eventQueue();

    // Handle interrupts on the eventQueue - so we don't do things in interrupt context

    // Toggle the built-in LED every second (until we're connected, see `registered` function)
    connectivityTicker.attach(eventQueue->event(&toggleConnectivityLed), 1.0f);

    // Functions can be executed through mbed Device Connector via POST calls (also defer to the event thread, so we never block)
    client.define_function("led/0/play", eventQueue->event(&play));

    // Connect to the internet (see mbed_app.json for the connectivity method)
    NetworkInterface* network = easy_connect(true);
    if (!network) {
        return 1;

    // Connect to mbed Device Connector
    struct MbedClientOptions opts = client.get_default_options(); // opts contains information like the DeviceType
    bool setup = client.setup(opts, network);
    if (!setup) {
        printf("Client setup failed\n");
        return 1;