MQTT

I was originally looking at MQTT right now in the context of Presence Detection. It turned out that Home Assistant already had a good integration with UniFi so I stopped working on that. Now I am building an ESP8266 Arduino (WeMos D1) light strip controller.

My Mosquitto MQTT Server is in a docker container on Bellman. I can log into that container and run commands to learn more.

Listen for presence messages from anyone. QOS is set to 'at least once'. -d is for debug. -t defines what I listen to, where the "+" is a wildcard.

docker exec -it mosquitto mosquitto_sub -t 'sensors/+/presence' -q 1 -d
docker exec -it home-assistant_mosquitto_1 mosquitto_sub -t 'WEMOS/#' -q 1 -d

Send a message.

docker exec -it mosquitto mosquitto_pub -t 'sensors/unifi/presence' -q 1 -d -m 'Julie arrived'
docker exec -it home-assistant_mosquitto_1 mosquitto_pub -t HOME -q 1 -d -m "`date +%H:%M:%S`"

How should my messages look?

• PUB Home Assistant will publish desired LED settings.
• SUB The Arduino will subscribe and adjust the LEDs accordingly.
• PUB After making changes the Arduino will send current settings. On power up the Arduino will restore the last state of the strip and send status.
• SUB Home Assistant will subscribe and display the LED settings.

I should be able to mock both sides with a bit of Python.

Python for testing

conda create --name mqtt
conda activate mqtt
conda install -c conda-force paho-mqtt

Here's my very first program. It sends a 1 or a 0 to whatever wants to hear it.

import paho.mqtt.publish as publish
import time

HOST = "192.168.123.2"
state = True
target = "blinker"

while(1):
    print(state)
    publish.single(target, "1" if state else "0", hostname=HOST)
    time.sleep(1)
    state = not state

Arduino

Now I need to make the WeMos D1 listen and respond. First I tried the Adafruit library and their sample code. It works, but the MQTT server is out there in the cloud and interfaces with a web page at Adafruit. I want to keep a lid on things.

Per the article in the Resources section I am trying PubSubClient which can be installed from the Library Manager in the Arduino IDE.

I wrote my own little MQTT program that just communicated with RGBW numbers, like this: 0100 0100 0300 0400. It worked great and I was able to send commands from the MQTT console in the Developer section of Home Assistant. Then I found this: https://github.com/corbanmailloux/esp-mqtt-rgb-led

I used the name mqtt-hallway and topics state: home/rgbw and command: home/rgbw/set.

Android MQTT clients

It looks like having multiple Android MQTT clients does not work. So from now on I am testing one at a time.

I want one that can display text messages. I'd also like it to make sounds. I still have not found an app that will display a series of text messages. They just display the most recent.

I avoid any that "contain ads" and most of the ones that cost $.

There are specialized clients, for example one to watch a doorbell and one to arm/disarm security systems. There is one for OBD2 called "Car IoT". Some free clients require using a cloud-based broker.

In evaluation...

1. MyMQTT - will display a list of messages from the same topic!! ON TABLET
2. Linear MQTT Dashboard - fancy charting, notifications are good; ON PHONE
3. MQTT Dash - simple and works. Text display is weak.
4. MQTT Snooper - runs in foreground only, contains ads

More...

1. MQTT IoT
2. MQTT Terminal costs $.99
3. MQTT Alert, 10 installs
4. Lazy MQTT Free (ad supported) or Pro ($30)

Rejected

1. MQTT Chat (Remnum)
2. MQTT Push Client (Helios) - uses a push notification services
3. Wallpanel -- Google text-to-speech, face detection (-1), complex
4. MQTIZER - chat style display; but appears to do nothing
5. MQTT Notification - just shows a popup, does nothing else

Resources

Books - in Safari

• Hands-on MQTT Programming With Python Gaston Hillar. Overview, not much python here
• Getting Started with Python for the Internet of Things

https://www.baldengineer.com/mqtt-tutorial.html