Connect ANX Dev Module to Wi-Fi and Cloud MQTT

This example shows you how to connect your ANX dev module to a Wi-Fi network and publish sensor data to an MQTT broker using TLS — the foundation for any cloud-connected IoT project. By the end you’ll have a device that automatically reconnects to your network on boot, reads the onboard ADC, and streams JSON payloads to a topic of your choice every five seconds.

Prerequisites

Before you flash this example, make sure you have the following ready:

Your Wi-Fi SSID and password (2.4 GHz network — the ANX dev module does not support 5 GHz)
Access to an MQTT broker with TLS on port 8883 — HiveMQ Cloud free tier works out of the box, or run a local Mosquitto instance
ANX dev module running firmware 1.1.0 or later (TLS support was added in 1.1.0)

Configure Wi-Fi and MQTT

All runtime credentials live in config.json at the root of the example directory. Open the file and replace the placeholder values with your own before flashing — the ANX OS reads this file at boot and passes the settings to the Wi-Fi and MQTT drivers automatically.

config.json

{
  "wifi": {
    "ssid": "YourNetwork",
    "password": "YourPassword",
    "mode": "station"
  },
  "mqtt": {
    "host": "broker.hivemq.com",
    "port": 8883,
    "tls": true,
    "client_id": "anx-device-001",
    "username": "your-username",
    "password": "your-password"
  }
}

Never hard-code your Wi-Fi password, MQTT username, or MQTT password directly in source code. Credentials embedded in .c files are trivial to extract from a compiled firmware binary and will end up in version control. Always place secrets in config.json, which is excluded from the examples repository by .gitignore.

Application Code

The application connects to Wi-Fi, establishes a TLS-secured MQTT session, then enters a loop that reads the ADC, formats a JSON payload, and publishes it every five seconds.

connectivity.c

#include "anx/anx.h"
#include "anx/wifi.h"
#include "anx/mqtt.h"
#include "anx/adc.h"
#include "anx/log.h"
#include <stdio.h>

#define TOPIC "anx/device/sensors"

void app_main(void) {
    // Connect to Wi-Fi (reads ssid/password from config.json)
    anx_wifi_connect();
    ANX_LOGI("WiFi", "Connected. IP: %s", anx_wifi_get_ip());

    // Connect to MQTT broker (reads host/port/tls from config.json)
    anx_mqtt_connect();
    ANX_LOGI("MQTT", "Connected to broker");

    // Init ADC
    anx_adc_init(ANX_ADC0);

    while (1) {
        // Read sensor
        uint16_t raw     = anx_adc_read(ANX_ADC0);
        float    voltage = (raw / 4095.0f) * 3.3f;

        // Build JSON payload
        char payload[64];
        snprintf(payload, sizeof(payload),
                 "{\"voltage\":%.2f,\"raw\":%d}", voltage, raw);

        // Publish
        anx_mqtt_publish(TOPIC, payload, ANX_MQTT_QOS1);
        ANX_LOGI("MQTT", "Published: %s", payload);

        anx_delay_ms(5000);
    }
}

Run and Verify

Flash the example and open the serial monitor to confirm that both the Wi-Fi and MQTT connections succeed before the publish loop begins:

anx run examples/connectivity
anx monitor

Within a few seconds of the module resetting you should see:

[WiFi] Connected. IP: 192.168.1.42
[MQTT] Connected to broker
[MQTT] Published: {"voltage":1.65,"raw":2048}

A new Published line appears every five seconds. If the Wi-Fi connection drops, anx_wifi_connect() automatically retries in the background — MQTT publishes resume once the link is restored.

Subscribing to Messages

To verify that your payloads are actually reaching the broker, subscribe to the same topic from your desktop using the mosquitto_sub CLI client:

mosquitto_sub -h broker.hivemq.com -p 8883 --capath /etc/ssl/certs \
  -u your-username -P your-password -t "anx/device/sensors"

Each time your device publishes you’ll see a line like the following printed to your terminal:

{"voltage":1.65,"raw":2048}

Linux / macOS
Windows

Install mosquitto-clients via your package manager (apt install mosquitto-clients or brew install mosquitto), then run the mosquitto_sub command above. The --capath /etc/ssl/certs flag points to the system CA bundle, which is sufficient for public brokers such as HiveMQ Cloud.

Download the Mosquitto installer from mosquitto.org. After installation, open a Command Prompt in the Mosquitto directory and replace --capath /etc/ssl/certs with --cafile "C:\Program Files\mosquitto\certs\ca-bundle.crt" in the subscribe command.

ANX OS bundles a current set of root CA certificates in the firmware image, so setting "tls": true in config.json is all you need for TLS to work — there is no certificate provisioning step on the device side. The bundled CA store is updated with each ANX OS release; keep your firmware current to stay compatible with broker certificate renewals.

Get Started

Dev Module

OS Firmware

Example Applications

Troubleshooting

Connect ANX Dev Module to Wi-Fi and Cloud MQTT

Prerequisites

Configure Wi-Fi and MQTT

Application Code

Run and Verify

Subscribing to Messages

​Prerequisites

​Configure Wi-Fi and MQTT

​Application Code

​Run and Verify

​Subscribing to Messages

Prerequisites

Configure Wi-Fi and MQTT

Application Code

Run and Verify

Subscribing to Messages