Adding MQTT connection to your UI
At some point you may want to connect your UI to a Pub Sub service like MQTT. Here is some example code that uses the miniMQTT and PyPortal libraries to connect with a hosted MQTT server. See is you can add some of these UI elements to the example.
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
import time
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
import adafruit_pyportal
import adafruit_minimqtt.adafruit_minimqtt as MQTT
pyportal = adafruit_pyportal.PyPortal()
### WiFi ###
# Get wifi details and more from a secrets.py file
try:
from secrets import secrets
except ImportError:
print("WiFi secrets are kept in secrets.py, please add them there!")
raise
# ------------- MQTT Topic Setup ------------- #
mqtt_topic = "test/topic"
### Code ###
# Define callback methods which are called when events occur
# pylint: disable=unused-argument, redefined-outer-name
def connected(client, userdata, flags, rc):
# This function will be called when the client is connected
# successfully to the broker.
print("Subscribing to %s" % (mqtt_topic))
client.subscribe(mqtt_topic)
def disconnected(client, userdata, rc):
# This method is called when the client is disconnected
print("Disconnected from MQTT Broker!")
def message(client, topic, message):
"""Method callled when a client's subscribed feed has a new
value.
:param str topic: The topic of the feed with a new value.
:param str message: The new value
"""
print("New message on topic {0}: {1}".format(topic, message))
# Connect to WiFi
print("Connecting to WiFi...")
pyportal.network.connect()
print("Connected!")
# Initialize MQTT interface with the esp interface
# pylint: disable=protected-access
MQTT.set_socket(socket, pyportal.network._wifi.esp)
# Set up a MiniMQTT Client
mqtt_client = MQTT.MQTT(
broker=secrets["broker"],
username=secrets["user"],
password=secrets["pass"],
is_ssl=False,
)
# Setup the callback methods above
mqtt_client.on_connect = connected
mqtt_client.on_disconnect = disconnected
mqtt_client.on_message = message
# Connect the client to the MQTT broker.
mqtt_client.connect()
photocell_val = 0
while True:
# Poll the message queue
mqtt_client.loop()
# Send a new message
print("Sending photocell value: %d" % photocell_val)
mqtt_client.publish(mqtt_topic, photocell_val)
photocell_val += 1
time.sleep(1)
