README.md

AtomVM MQTT Client Example Program

The mqtt_client_example program illustrates use of the MQTT API by connecting to a well-known MQTT broker, and sending and receiving a message on a topic every 5 seconds. Results are displayed on the console.

Note. Building and flashing the mqtt_client_example program requires installation of the rebar3 Erlang build tool.

Start my copying the src/config.erl-template file to src/config.erl and edit the ssid and psk entries to match your environment.

get() ->
    #{
        sta => [
            {ssid, "myssid"},
            {psk, "mypassword"}
        ]
    }.

Build the example program and flash to your device:

shell$ rebar3 packbeam -p
shell$ rebar3 esp32_flash -p /dev/ttyUSB0

Note. This build step makes use of the atomvm_rebar3_plugin. See the README.md for information about parameters for setting the serial port and baud rate for your platform.

Attach to the console using minicom or equivalent:

shell$ minicom -D /dev/ttyUBS0
...
I (1789) NETWORK: SYSTEM_EVENT_STA_CONNECTED received.
I (2899) event: sta ip: 192.168.211.53, mask: 255.255.255.0, gw: 192.168.211.1
I (2899) NETWORK: SYSTEM_EVENT_STA_GOT_IP: 192.168.211.53
Acquired IP address: {192,168,211,53} Netmask: {255,255,255,0} Gateway: {192,168,211,1}
I (2939) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (2939) atomvm_mqtt: MQTT_EVENT_BEFORE_CONNECT msg_id: 0
MQTT started.
Connected to "mqtt://mqtt.eclipseprojects.io"; subscribing to <<"atomvm/qos0">>...
Subscribed to <<"atomvm/qos0">>.
Publishing data on topic <<"atomvm/qos0">>
Received data on topic <<"atomvm/qos0">>: echo
Publishing data on topic <<"atomvm/qos0">>
Received data on topic <<"atomvm/qos0">>: echo
Publishing data on topic <<"atomvm/qos0">>
Received data on topic <<"atomvm/qos0">>: echo
Publishing data on topic <<"atomvm/qos0">>
Received data on topic <<"atomvm/qos0">>: echo
...