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MQTT

The nRF9151 modem supports MQTT natively via Nordic’s AT#XMQTT* command set. The Modem class wraps these commands with validation and error handling.

Nordic reference: MQTT client AT commands — nCS 3.0.0

Prerequisites

Section titled “Prerequisites”

The modem must be on with network access enabled:

from modem import Modem


m = Modem()
m.CFUN(1)   # full functionality — wait for network registration

Configure the MQTT client

Section titled “Configure the MQTT client”
m.mqtt_cfg(
    client_id="my-device-01",
    keep_alive=60,      # seconds, default 60
    clean_session=1,    # 0 = persistent session, 1 = clean
)

Connect to a broker

Section titled “Connect to a broker”
connected = m.mqtt_conn(
    op=1,                       # 1 = connect IPv4, 2 = connect IPv6, 0 = disconnect
    username="user",
    password="secret",
    url="broker.example.com",
    port=1883,
    # sec_tag=1,               # optional TLS security tag
)
print(connected)   # True on success

Check connection status

Section titled “Check connection status”
print(m.is_mqtt_conn())   # True if currently connected

Publish a message

Section titled “Publish a message”
m.mqtt_publish(
    topic="sensors/temp",
    msg="23.4",
    qos=0,      # 0, 1, or 2
    retain=0,   # 0 or 1
)

Subscribe to a topic

Section titled “Subscribe to a topic”
m.mqtt_subscribe(topic="commands/#", qos=1)

Unsubscribe

Section titled “Unsubscribe”

mqtt_unsubscribe is not yet implemented in the Modem class. Use send_cmd directly:

m.send_cmd('AT#XMQTTUNSUB="sensors/#"', expected="#XMQTTEVT: 8,0", timeout_ms=5000)

Disconnect

Section titled “Disconnect”
m.mqtt_conn(op=0, username="", password="", url="", port=1)

Read current MQTT configuration

Section titled “Read current MQTT configuration”
print(m.get_mqtt_cfg())   # returns the raw #XMQTTCFG response line

See the Modem API reference for the full #XMQTTEVT event table and parameter details.