Golioth just rolled out a new settings service that lets you control your growing fleet of IoT devices. You can specify settings for your entire fleet, and override those global settings by individual device or for multiple devices that share the same blueprint.

Every IoT project needs some type of settings feature, from adjusting log levels and configuring the delay between sensor readings, to adjusting how frequently a cellular connection is used in order to conserve power. With the new settings service, the work is already done for you. A single settings change on the Golioth web console is applied to all devices listening for changes!

As you grow from dozens of devices to hundreds (and beyond), the Golioth settings service makes sure you can change device settings and confirm that those changes were received.

Demonstrating the settings service

Golioth settings service

The settings service is ready for you use right now. We have code samples for the Golioth Zephyr SDK and the Golioth ESP-IDF SDK. Let’s take it for a spin using the Zephyr samples.

I’ve compiled and flashed the Golioth Settings sample for an ESP32 device. It observes a LOOP_DELAY_S endpoint and uses that value to decide how long to wait before sending another “Hello” log message.

Project-wide settings

On the Golioth web console, I use the Device Settings option on the left sidebar to create the key/value pair for this setting. This is available to all devices in the project with firmware that is set up to observe the LOOP_DELAY_S settings endpoint.

Golioth device settings dialog

When viewing device logs, we can see the setting is observed as soon as the device connects to Golioth. The result is that the Hello messages are now issued ten seconds apart.

[00:00:19.930,000] <inf> golioth_system: Client connected!
[00:00:20.340,000] <inf> golioth: Payload
                                  a2 67 76 65 72 73 69 6f  6e 1a 62 e9 99 c4 68 73 |.gversio n.b...hs
                                  65 74 74 69 6e 67 73 a1  6c 4c 4f 4f 50 5f 44 45 |ettings. lLOOP_DE
                                  4c 41 59 5f 53 fb 40 24  00 00 00 00 00 00       |[email protected]$ ......  
[00:00:20.341,000] <dbg> golioth_hello: on_setting: Received setting: key = LOOP_DELAY_S, type = 2
[00:00:20.341,000] <inf> golioth_hello: Set loop delay to 10 seconds
[00:00:20.390,000] <inf> golioth_hello: Sending hello! 2
[00:00:30.391,000] <inf> golioth_hello: Sending hello! 3
[00:00:40.393,000] <inf> golioth_hello: Sending hello! 4

Settings by device or by blueprint

Of course, you don’t always want to have the same settings for all devices. Consider debugging a single device. It doesn’t make much sense to turn up the logging level or frequency of sensor reads for all devices. So with Golioth it’s easy to change the setting on just a single device.

settings change for a single device on the Golioth console

In the device view of the Golioth web console there is a settings tab. Here you can see the key, the value, and the level of the value. I have already changed the device-specific value in this screen so the level is being reported as “Device”.

[00:07:30.466,000] <inf> golioth_hello: Sending hello! 45
[00:07:40.468,000] <inf> golioth_hello: Sending hello! 46
[00:07:43.728,000] <inf> golioth: Payload
                                  a2 67 76 65 72 73 69 6f  6e 1a 62 e9 9c 17 68 73 |.gversio n.b...hs
                                  65 74 74 69 6e 67 73 a1  6c 4c 4f 4f 50 5f 44 45 |ettings. lLOOP_DE
                                  4c 41 59 5f 53 fb 40 00  00 00 00 00 00 00       |[email protected] ......  
[00:07:43.729,000] <dbg> golioth_hello: on_setting: Received setting: key = LOOP_DELAY_S, type = 2
[00:07:43.729,000] <inf> golioth_hello: Set loop delay to 2 seconds
[00:07:50.469,000] <inf> golioth_hello: Sending hello! 47
[00:07:52.471,000] <inf> golioth_hello: Sending hello! 48

When I made the change. the device was immediately notified and you can see from the timestamps that it began logging at a two-second cadence as expected.

Golioth settings applied at the blueprint level

It is also possible to change settings for a group of devices that share a common blueprint. Here you will find this setting by selecting Blueprint from the left sidebar and choosing your desired blueprint.

Settings are applied based on specificity. The device-level is the most specific and will be applied first, followed by blueprint-level, and finally project-level. Blueprints may be created and applied at any time, so if you later realize you need a more specific group you can change the blueprint for those devices.

Implementation: The two parts that make up the settings service

Fundamentally, there are two parts that make our device settings system work: the Golioth cloud services running on our servers and your firmware that is running on the devices. The Golioth device SDKs allow you to register a callback function that receives settings values each time a change is made to the settings on the cloud. You choose how the device should react to these settings, like updating a delay value, enabling/disabling features, changing log output levels, really anything you want to do.

Don’t worry if you already have devices in the field. You can add the settings service or make changes to how your device handles those settings, then use the Golioth OTA firmware update system to push out the new behavior.

Take control of your fleet

Scale is the hope for most IoT companies, but it’s also where the pain of IoT happens. You need to know you can control your devices, securely communicate with them, and perform updates as necessary. Golioth has you covered in all of these areas. The new settings service ensures that your ability to change how your fleet is performing doesn’t become outpaced by your growth.

NXP RT1060-EVKB Ethernet development board

I get to work with a lot of different hardware here at Golioth, but recently I’ve found my self gravitating to the NXP i.MX RT1060-EVKB evaluation board as my go-to development hardware. This brand new board is a variation on the RT1060-EVK, which (in addition to the extra ‘B’ in the new part number) adds an m.2 slot. But what catches my eye is the Ethernet. While I’ve previously written about using SPI-connected Ethernet modules, this board builds the connectivity right in. It’s stable, it’s fast, and has wonderful support in Zephyr.

The microcontroller that controls everything is the RT1062 which I first heard about three years back when the Teensy 4.0 was released. A 600 MHz powerhouse, it boasts 1024 kB of SRAM and is packed with peripherals. It’s an embarrassment of riches for my day-to-day firmware work, but makes sure I’ll never hit my head on the proverbial “development ceiling”.

Of course it’s not just the system clock that I’m happy about. This board has Ethernet built-in, so I’m not waiting for a WiFi connection (or really waiting for a cell connection) at boot. And it’s programmed via J-Link for a fast flash process and the RTT and debugging features that this programmer brings to the party.

Let’s take a look at how I get this board talking to Golioth, and what we might see in the near future.

An i.MX RT1060-EVKB demo

NXP RT1060-evkb webinar demo

Demonstrating Golioth LightDB Stream for temperature/pressure/humidity sensor data

A couple of weeks ago I did a demo of the i.MX RT1060-EVKB board as part of NXP’s Zephyr webinar series. It gives you a great overview of the board and the ecosystem. I was even able to do a live demo of all the Golioth features like data management, command/control, remote logging, and OTA firmware updates. (Requires a free NXP registration to see the video.)

This board already has great support with the Golioth platform. My hope is to go further than that and add this to our list of Continuously Verified Boards. This would mean that we test and verify all official Golioth code samples with this board during every Golioth release. That’s a tall hill to climb, but it would be a snap if we used automated testing through a process called Hardware in the Loop; CI/CD that automatically runs compiled code on the hardware itself. This is already the case for our recently announced Golioth ESP-IDF SDK. Nick Miller is working on a post about how he pulled that off, so keep your eyes on the Golioth Blog over the next couple of weeks!

Get your tools ready

To build for this board you need a few tools, like the HAL library for NXP, LVGL, and the board files themselves.

Adding the NXP HAL and the LVGL library

Zephyr needs a hardware abstraction layer for NXP builds, and this board also depends on having the LVGL library installed. Add these to your west manifest:

  • use the west manifest --path to help you locate which file to edit (modules/lib/golioth/west-zephyr.yml in my case)
  • Add hal_nxp and lvgl to the name-allow list
  • Run west update

With the edits in place, here’s what the relevant section of my west manifest looks like:

manifest:
  projects:
    - name: zephyr
      revision: v3.1.0
      url: https://github.com/zephyrproject-rtos/zephyr
      west-commands: scripts/west-commands.yml
      import:
        name-allowlist:
          - cmsis
          - hal_espressif
          - hal_nordic
          - mbedtls
          - net-tools
          - segger
          - tinycrypt
          - hal_nxp
          - lvgl

Cherry Pick the EVKB files (if needed)

This is a new board and the devicetree files for it were just added to Zephyr on Jun 5th. My Zephyr is still on v3.1.0 so it’s older than the commit that added support for the “evkb” board. I used git’s cherry-pick feature to add those files to my workspace. From the golioth-zephyr-workspace/zephyr directory run:

git pull
git cherry-pick 9a9aeae00b184cac308c1622676bb91c07dd465b

This will pull in just the commit that adds support for the new board.

Thar ‘b dragons

Here’s the thing about making manual changes to the Zephyr repo in your workspace: the west manifest doesn’t know you’ve done this. That means the next time you run west update, this cherry-picked commit will be lost.

Prep the hardware

Last, but not least, I used a J-Link programmer to flash firmware to this board. There’s just a bit of jumper setup necessary to make this all work. NXP has a guide to setting up an external J-Link programmer. I followed that page, using a USB cable on J1 for power (and a serial terminal connection when running apps).

Saying Hello

With that preamble behind me, I’m excited to get to the “Hello” part of things using the standard Golioth Hello sample. Running Golioth samples is fairly easy with this board, with just one puzzle piece that needs to be added for DHCP to acquire an IP address.

Use DHCP to get an IP address

I added a boards/mimxrt1060_evkb.conf file to create a configuration specific to this board. In this case, it selects the Ethernet and DHCP libraries.

CONFIG_NET_L2_ETHERNET=y
CONFIG_NET_DHCPV4=y

At the top of main.c I include the network interface library. Then in the main() function, we need to instantiate an interface and pass it to the DHCP function. This code requests an IP address from the network’s DHCP server.

#include <net/net_if.h>
struct net_if *iface;
LOG_INF("Run dhcpv4 client");
iface = net_if_get_default();
net_dhcpv4_start(iface);

client->on_message = golioth_on_message;
golioth_system_client_start();

Add credentials, then build and flash

The final step is to add your Golioth credentials before building and flashing the app. Add the credentials to the prj.conf file as outlined in the hello sample README. You can get your credentials by creating a new device on the Golioth Console.

CONFIG_GOLIOTH_SYSTEM_CLIENT_PSK_ID="my-psk-id"
CONFIG_GOLIOTH_SYSTEM_CLIENT_PSK="my-psk"

The build calls out the board name to specifically target our board and the newly added configuration. The flash command will automatically find the J-Link programmer and use it.

west build -b mimxrt1060_evkb samples/hello
west flash

In my testing it only took about three seconds to get an IP address. From there, I was up and connected to Golioth after just another two seconds!

Golioth Hello serial terminal output

Golioth Hello example output

Off to the races

There really isn’t much to getting this up and running. Once I worked through this process I was able to test out all of the Golioth samples, including using the terminal shell to provision the board (ie: adding the Golioth credentials) and performing Over-the-Air (OTA) firmware updates.

As I mentioned earlier, the speed and reliability of this dev board keeps drawing me back. It’s not just the initial connection, but when testing out OTA, the 1024 byte block downloads seem to fly right by. I’m unsure if this is the Ethernet or the chip’s ability to quickly write to flash, but if you’re working with a 250 kB firmware file the difference over, say an ESP32, is obvious.

Give it a try using Golioth’s Dev Tier which includes up to 50 devices for your test fleet. The Golioth forum is a great place for questions on the process, and we’d love to hear about what you’re building over on the Golioth Discord server.

Keep your eye on this space. When Zephyr issues its next release we’ll roll forward the Golioth SDK to include the board files for the RT1060-EVKB, and my hope is that we’ll be able to include the DHCP call into our common samples code for a truly out-of-the-box build experience. We might even see a bit of that Hardware-in-the-Loop build automation I hinted at earlier. See you next time!

On Tuesday we announced the Golioth ESP-IDF SDK that delivers all of Golioth’s excellent features to ESP32 projects built on Espressif’s FreeRTOS-based ESP-IDF ecosystem. The APIs included in our SDK make it dead simple to set up an encrypted connection with Golioth and begin sending and receiving data, controlling the device remotely, sending your logging messages up to the cloud, and of course performing Over-the-Air (OTA) updates on remote devices.

Today we dive into the code as Nick Miller, Golioth’s lead firmware engineer, takes us on a guided tour.

What does Golioth ESP-IDF SDK deliver?

All of the best features of Golioth’s device management cloud are available in our ESP-IDF SDK. The set of APIs are quite clever and take all of the heavy lift out of your hands. This includes:

  • Set, get, and observe data endpoints on the cloud
  • Write log data back to the cloud
  • Handle Over-the-Air (OTA) firmware updates
  • API calls–in both synchronous and asynchronous options–to suit your needs

Setup: Install ESP-IDF and clone the Golioth repo

To get started you need have the ESP-IDF installed and clone the Golioth ESP-IDF SDK. Instructions are available in the readme of our git repository, and there is also a quickstart on our docs site.

Our new SDK is a component for FreeRTOS, the real-time operating system used by the ESP-IDF. It’s the same operating system and build tools you’re used to, with the Golioth SDK sitting on top so that your devices can interact with the Golioth servers.

Stepping through the Golioth-Basics example

The best way to test-drive is with the Golioth-Basics example that is included in the SDK. It demonstrates assigning Golioth credentials to your device, sending/receiving data, observing data, sending log messages, and performing over-the-air (OTA) firmware updates. The app_main.c file is thoroughly commented to explain each API call in detail.

The example begins by initializing non-volatile storage, configuring a serial shell, checking for credentials, and connecting to WiFi. At that point we can start using the Golioth APIs.

Creating the Golioth system client

// Now we are ready to connect to the Golioth cloud.
//
// To start, we need to create a client. The function golioth_client_create will
// dynamically create a client and return a handle to it.
//
// The client itself runs in a separate task, so once this function returns,
// there will be a new task running in the background.
//
// As soon as the task starts, it will try to connect to Golioth using the
// CoAP protocol over DTLS, with the PSK ID and PSK for authentication.
golioth_client_t client =
        golioth_client_create(nvs_read_golioth_psk_id(), nvs_read_golioth_psk());

Everything starts of by instantiating a client to handle the connection for you. This client will be passed to all of the API calls so that the SDK knows where to send them.

Sending log messages

// We can also log messages "synchronously", meaning the function will block
// until one of 3 things happen (whichever comes first):
//
// 1. We receive a response to the request from the server
// 2. The user-provided timeout expires
// 3. The default client task timeout expires (GOLIOTH_COAP_RESPONSE_TIMEOUT_S)
//
// In this case, we will block for up to 2 seconds waiting for the server response.
// We'll check the return code to know whether a timeout happened.
//
// Any function provided by this SDK ending in _sync will have the same meaning.
golioth_status_t status = golioth_log_warn_sync(client, "app_main", "Sync log", 5);

Here you can see a log being written to Golioth. Notice that the client created in the previous code block is used as the first parameter. This logging call is synchronous, and will wait to ensure the log was received by the Golioth servers. There is also an asynchronous version available that provides the option to run a callback function when the log is received by Golioth.

Setting up OTA firmware updates

// For OTA, we will spawn a background task that will listen for firmware
// updates from Golioth and automatically update firmware on the device using
// Espressif's OTA library.
//
// This is optional, but most real applications will probably want to use this.
golioth_fw_update_init(client, _current_version);

OTA firmware updates are handled for you by the SDK. The line of code shown here is all it takes to register for updates. The app will then observe the firmware version available on the server. It will automatically begin the update process whenever you roll out a new firmware release on the Golioth Cloud.

Sending and receiving data

// There are a number of different functions you can call to get and set values in
// LightDB state, based on the type of value (e.g. int, bool, float, string, JSON).
golioth_lightdb_set_int_async(client, "my_int", 42, NULL, NULL);
// To asynchronously get a value from LightDB, a callback function must be provided
golioth_lightdb_get_async(client, "my_int", on_get_my_int, NULL);

The bread and butter of the IoT industry is the ability to send and received data. This code demonstrates asynchronous set and get functions. Notice that the get API call registers on_get_my_int as a callback function that will be executed to handle the data that arrives back from the Golioth servers.

A get command runs just once to fetch the requested data from Golioth. Another extremely useful approach is to observe the data using the golioth_lightdb_observe_async(). It works the same way as an asynchronous get call, but it will execute your callback every time the data on the server changes.

Putting it all together

In the second half of the video, Nick takes us through the process running the demo. He starts with setting up the ESP-IDF environment and compiling to code, and continues all the way through to viewing the device data on the web console.

You’re going to love working with the Golioth ESP-IDF SDK. It’s designed to deal with all the complexity of securely connecting and controlling your IoT devices. The API calls are easy to understand, and they make it painless to add Golioth to existing and future ESP-IDF based projects. Give it a try today using our free Dev Tier.

We’d love to hear what you’re planning to build. You can connect with us on the Golioth Discord server, ask questions over on the Golioth Forums, and share your demos by tagging the Golioth account on Twitter.

One of the most useful services in the Golioth Zephyr SDK is the ability to observe data changes on the cloud. A device can register any LightDB endpoint and the Golioth servers will notify it whenever changes happen. If your device is a door lock, an example endpoint might be “lock status”, which you would want to know about a server-side state change immediately.

This is slightly more complex to set up than something like a LightDB ‘Set’ API call. ‘Observe’ requires a callback function to handle the asynchronous reply from the Golioth servers. Today we’ll walk through how to add Golioth LightDB Observe functionality to any Zephyr application by:

  1. Adding a callback that is called every time observed data changes
  2. Registering the callback with a data endpoint
  3. Using on_message to trigger the callback
  4. Ensuring that on_message and on_connect are both registered

These techniques are all found in our LightDB Observe sample code which acts as the roadmap for this article.

Prerequisites

Today’s post assumes that you already have a device running Zephyr and you have already tested out an app that uses the Golioth Zephyr SDK. If you’re not there yet, don’t worry. You can sign up for our free Dev Tier that includes up to 50 devices, and follow the Golioth Quickstart Guide.

Your Zephyr workspace should already have Golioth installed as a module and your app (probably in main.c) is already instantiating a Golioth system client. Basically, you should see a block like this one somewhere in your code:

#include <net/coap.h>
#include <net/golioth/system_client.h>
static struct golioth_client *client = GOLIOTH_SYSTEM_CLIENT_GET();

If you don’t, checkout out our How to add Golioth to an existing Zephyr project blog post to get up to speed before moving on.

1. Add a callback function for observed data changes

The goal of this whole exercise is to enable your device to perform a task whenever data changes at your desired endpoint. Remember: Golioth LightDB endpoints are configurable by you! Whatever data you’d like to monitor, you can customize it to your needs.

The first thing we’ll do is create a callback function that will perform the task.

static int on_update(const struct coap_packet *response,
             struct coap_reply *reply,
             const struct sockaddr *from)
{
    char str[64];
    uint16_t payload_len;
    const uint8_t *payload;

    payload = coap_packet_get_payload(response, &payload_len);
    if (!payload) {
        LOG_WRN("packet did not contain data");
        return -ENOMSG;
    }

    if (payload_len + 1 > ARRAY_SIZE(str)) {
        payload_len = ARRAY_SIZE(str) - 1;
    }

    memcpy(str, payload, payload_len);
    str[payload_len] = '\0';

    LOG_DBG("payload: %s", log_strdup(str));

    return 0;
}

 

The majority of this callback is used to verify that string data was received from Golioth. Ultimately, line 22 is what you are interested in. For this example, we’re printing a log message with the string payload stored in the str array.

If your endpoint contains more than just one value, it may be useful to parse the JSON object and store the values. Also keep in mind that this callback will execute on the golioth system client thread, which is a different thread than the “main” thread running your application. This means:

  • The callback function should return quickly (under 10 ms). If that’s not enough time, you can use a Zephyr Workqueue to schedule the work on another thread.
  • If access to global data is required, access to the data must be protected by a mutex to avoid data races between threads.

2. Add coap_reply and register the callback in on_connect

We need to create an array of structs to store messages that arrive from Golioth. This struct is then registered with an endpoint and the callback we created in step 1.

#include <net/coap.h>

First ensure that you have included the CoAP header from Zephyr which defines the coap_reply struct and has some handy helper functions.

static struct coap_reply coap_replies[1];

Here I’ve created a coap_replies array with just one member because my example observes one single endpoint. If you want to observe multiple endpoints, you will need multiple callbacks and you must have one coap_reply for each callback.

static void golioth_on_connect(struct golioth_client *client)
{
    struct coap_reply *observe_reply;
    int err;

    coap_replies_clear(coap_replies, ARRAY_SIZE(coap_replies));

    observe_reply = coap_reply_next_unused(coap_replies, ARRAY_SIZE(coap_replies));

    /*
     * Observe the data stored at `/counter` in LightDB.
     * When that data is updated, the `on_update` callback
     * will be called.
     * This will get the value when first called, even if
     * the value doesn't change.
     */
    err = golioth_lightdb_observe(client,
                      GOLIOTH_LIGHTDB_PATH("counter"),
                      COAP_CONTENT_FORMAT_TEXT_PLAIN,
                      observe_reply, on_update);

    if (err) {
        LOG_WRN("failed to observe lightdb path: %d", err);
    }
}

Now we register the observation using the golioth_lightdb_observe() API call. The parameters passed to this function include:

  1. The endpoint to observe (the GOLIOTH_LIGHTDB_PATH macro indicates this is a LightDB State endpoint)
  2. The format, either plain text or CBOR (see the LightDB LED sample which demonstrates using CBOR serialization)
  3. A coap_reply struct to store the message and metadata received from Golioth
  4. The callback function to execute when a message is received from this endpoint

Notice that the helper function coap_reply_next_unused() is called to get the next available struct. This is important if you are registering multiple callbacks and should be used prior to each golioth_lightdb_observe() API call to get a pointer to a struct that isn’t already associated with another callback.

3. Add the processing function to on_message

This step is small but important, and seems to be the one I frequently forget and then scratch my head when my callback isn’t working.

Whenever a message is received from Golioth, the Golioth system client executes a callback that we usually call on_message. For our observed callbacks to work, we need to tell on_message about our coap_replies array.

static void golioth_on_message(struct golioth_client *client,
                   struct coap_packet *rx)
{
    /*
     * In order for the observe callback to be called,
     * we need to call this function.
     */
    coap_response_received(rx, NULL, coap_replies,
                   ARRAY_SIZE(coap_replies));
}

 

By calling Zephyr’s coap_response_received(), the CoAP packet will be parsed and the appropriate callback will be selected from the coap_replies struct (if one exists).

4. Ensure on_message and on_connect are both registered

The final step is to make sure that we’ve registered callbacks for when the Golioth system client connects and receives a message.

client->on_connect = golioth_on_connect;
client->on_message = golioth_on_message;
golioth_system_client_start();

This should be done in main() before the loop begins. The golioth_client struct should have already been instantiated in your code, in this example it was called client. The code above associates our two callbacks and starts the client running.

Observed data in action

Now that we’ve tied it all together, let’s test it out. Here’s the terminal output of my Zephyr app:

[00:00:09.328,000] <dbg> golioth_lightdb: main: Start Light DB observe sample
[00:00:09.328,000] <inf> golioth_system: Starting connect
[00:00:09.537,000] <inf> golioth_system: Client connected!
[00:00:09.739,000] <dbg> golioth_lightdb: on_update: payload: null
[00:00:48.653,000] <dbg> golioth_lightdb: on_update: payload: 42

You can see that at boot time, the observed data will be reported, which is great for setting defaults when your device first connects to observed data. When the endpoint was registered it didn’t exist on Golioth so a payload of null was returned. About 49 seconds later a payload of 42 is received. That’s when I added the endpoint and value in the Golioth Console.

On the cloud, this is an integer, but the device receives payloads as strings. You’ll need to validate received data on the device side to ensure expected behavior in your callback functions (beyond simply printing out the payload as I’m doing here). Give it a try for yourself using our LightDB Observe sample code.

Observing LightDB data gives your devices the ability to react to any changes without the need to poll like you would if you were using the golioth_lightdb_get() function. In addition to being notified each time the data changes, you’ll also get the current state when the observation is first registered (ie: at power-up). Single endpoints, or entire JSON objects can be observed, making it possible to group different types of state data to suit any need.

If you still have questions, or want to talk about how LightDB Observe works under the hood, head over to the Golioth Forum or ping us on the Golioth Discord.

Golioth is a device management cloud that is easy to add to any Zephyr project. Just list the Golioth Zephyr SDK as a module in your manifest file and the west tool will do the rest. Well, almost. Today I’ll walk through how to add Golioth to an existing Zephyr project. As an example, I’ll be using our hello sample. We chose this because it already has networking, which makes explaining things a bit easier. Generally any board that has led0 defined in the device tree and you can enable networking should be a good fit. What we want to do here is showcase the elements that allow you to add Golioth, so let’s dive in!

0. Understanding the west manifest

A Zephyr workspace is made up of a number of different code repositories all stored in the same tree. Zephyr uses a west manifest file to manage all of these repositories, including information like the origin URL of the repo, the commit hash to use, and where each repository should be placed in your local tree.

Think of the manifest as a code repository shopping list that the west update command uses to fill up your local Zephyr tree. There may be more than one manifest file, but today we’ll just focus on the main manifest.

1. Add Golioth to the west manifest

Start by locating your manifest file and opening it with a code editor.

~/zephyrproject $ west manifest --path
/home/mike/zephyrproject/zephyr/west.yml

Under projects: add an entry for the Golioth Zephyr SDK (highlighted in the abbreviated manifest sample below).

manifest:
  defaults:
    remote: upstream
 
  remotes:
    - name: upstream
      url-base: https://github.com/zephyrproject-rtos
 
  #
  # Please add items below based on alphabetical order
  projects:
      # Golioth repository.
    - name: golioth
      path: modules/lib/golioth
      revision: v0.2.0
      url: https://github.com/golioth/golioth-zephyr-sdk.git
      import:
        west-external.yml
    - name: canopennode
      revision: 53d3415c14d60f8f4bfca54bfbc5d5a667d7e724
...

Note that I have called out the v0.2.0release tag. You can set this to any of our release tags, to main, or to a specific commit.

Now run an update to incorporate the manifest changes:

west update

2. Select libraries to add to the build

We use KConfig to build in the libraries that Golioth needs. These changes are made in the prj.conf file of your application.

The first set of symbols deals with Zephyr’s networking stack. Of course every Internet of Things thing needs a network connection so you likely already have these symbols selected.

# Generic networking options
CONFIG_NETWORKING=y
CONFIG_NET_IPV4=y
CONFIG_NET_IPV6=n

Golioth is secure by default so we want to select the mbedtls libraries to handle the encryption layer.

# TLS configuration
CONFIG_MBEDTLS_ENABLE_HEAP=y
CONFIG_MBEDTLS_HEAP_SIZE=10240
CONFIG_MBEDTLS_SSL_MAX_CONTENT_LEN=2048

Now let’s turn on the Golioth libraries and give them a bit of memory they can dynamically allocate from.

# Golioth Zephyr SDK
CONFIG_GOLIOTH=y
CONFIG_GOLIOTH_SYSTEM_CLIENT=y
 
CONFIG_MINIMAL_LIBC_MALLOC_ARENA_SIZE=256

Every device needs its own credentials because all connections to Golioth require security. There are a few ways to do this, but perhaps the simplest is to add them to the prj.conf file.

# Golioth credentials
CONFIG_GOLIOTH_SYSTEM_CLIENT_PSK_ID="[email protected]"
CONFIG_GOLIOTH_SYSTEM_CLIENT_PSK="cab43a035d4fe4dca327edfff6aa7935"

And finally, I’m going to enable back-end logging. This is not required for connecting to Golioth, but sending the Zephyr logs to the cloud is a really handy feature for remote devices.

# Optional for sending Zephyr logs to the Golioth cloud
CONFIG_NET_LOG=y
CONFIG_LOG_BACKEND_GOLIOTH=y
CONFIG_LOG_PROCESS_THREAD_STACK_SIZE=2048

I separated each step above for the sake of explanation. But the combination of these into one block is the boiler-plate configuration that I use on all of my new projects. See this all as one file in the prj.conf from our hello sample.

3. Instantiate the Golioth system client and say hello

So far we added Golioth as a Zephyr module and enabled the libraries using KConfig. Now it’s time to use the Golioth APIs in the main.c file.

The first step is to include the header files and instantiate a golioth_client object. The client is used to manage the connection with the Golioth servers. Including the coap header file is not strictly required to establish a connection, but it is necessary for processing the responses from Golioth, so I always include it.

#include <net/coap.h>
#include <net/golioth/system_client.h>
static struct golioth_client *client = GOLIOTH_SYSTEM_CLIENT_GET();

I also add a callback function to handle messages coming back from the Golioth cloud. Technically this is optional, but if you want two-way communication with the cloud you need it!

/* Callback for messages received from the Golioth servers */
static void golioth_on_message(struct golioth_client *client,
                   struct coap_packet *rx)
{
    uint16_t payload_len;
    const uint8_t *payload;
    uint8_t type;
 
    type = coap_header_get_type(rx);
    payload = coap_packet_get_payload(rx, &payload_len);
 
    printk("%s\n", payload);
}

In the main function, I register my callback, start the Golioth client, and call the golioth_send_hello() API.

/* Register callback and start Golioth system client */
client->on_message = golioth_on_message;
golioth_system_client_start();
 
while (1) {
    /* Say hello to Golioth */
    int ret = golioth_send_hello(client);
    if (ret) {
        printk("Failed to send hello! %d\n", ret);
    }
    else printk("Hello sent!\n");
}

When successful, the golioth_send_hello() call will prompt for a message back from the server which includes the name of the sending device. This is printed out by the golioth_on_message() callback.

Hello sent!
Hello blinky1060
Hello sent!
Hello blinky1060
Hello sent!
Hello blinky1060

Extra Credit: Back-end Logging

Observant readers have noticed that I enabled back-end logging using KConfig symbols but I didn’t use it in the C code. Here’s the really awesome part: just use Zephyr logging as you normally would and it will automatically be sent to your Golioth console.

At the top of main.c, include the log header file and register a logging module.

#include <logging/log.h>
LOG_MODULE_REGISTER(any_name_you_want, LOG_LEVEL_DBG);

In our C functions, call logs as you normal would.

LOG_ERR("An error message goes here!");
LOG_WRN("Careful, this is a warning!");
LOG_INF("Did you now that this is an info log?");
LOG_DBG("Oh no, why isn't my app working? Maybe this debug log will help.");

Now your log messages will appear on the Golioth console!

Further Reading

This covers the basics of adding Golioth to an existing Zephyr project. You can see the steps all in one place by looking at the Golioth code samples. Here are the examples that you’ll find immediately useful:

  • Hello – basics of connecting to Golioth and sending log messages (what was covered in this post)
  • Lightdb Set – send data to Golioth
  • Lightdb Observe – device will be notified whenever an endpoint on the Golioth cloud is updated

To go even deeper, you can see how we use the Golioth Over-the-Air (OTA) firmware update feature, and how to use the Zephyr settings subsystem for persistent credential storage. And remember, the Dev Tier of Golioth includes the first 50 devices, so you can try all of this out for free.

Image from Todd Lappin on flickr