Generally speaking this is how I learned to cache a JSON object in a Node-RED flow with the Change node by setting a flow based variable. Specifically this handles a problem with HomeAssistants light card backed by a MQTT light (defined in the configuration.yaml) only emitting partial values of the light setting when updating. New…
I wanted to know which topics are active on my MQTT server and if there were some skeletons in the closet I could get rid of. Many Iot devices, Node-RED flows and surely some unused topics or old retained topics lead to more or less MQTT being a chaotic museum of topics. This is just…
I have a talent to forget to cover my car before a night with temperature below zero and the next morning I have to scratch away all the ice. As I really don’t like that I decided to build a warning mechanism for that. I already had a Node-RED flow querying the weather API to…
Precondition: Have your lokal MQTT broker and Node-RED installed and setup or access to a remote one. I recently added a http request node querying a weather API to Node-RED. After extracting, the current temperature is then published on the local MQTT and can be used by all devices connected to the broker.In this example…
TLDR: An IoT sensor for temperature and humidity sending its values to a local MQTT server. Measuring interval and thresholding easy to configure. So much to write about a pretty small device and less than 100 lines of code including configuration, prints and comments. Hope you enjoy it! 🙂 I really like building and writing…
TLDR: Measures temp&hum in a configurable interval and with variable thresholds. Publishes to a mqtt server. Neopixels react to json data at a mqtt topic it is configured to subscibe. Single thread async implementation. Robust wifi and mqtt routines. Code at my github: https://github.com/worksonmymachine-de/iot_temptumsensor_ambilight This device is placed behind my main monitor and reads temperature…
It measures the temperature, humidity and open status of a window and send the values to the local MQTT broker if the values have changed (enough). The D1 got a nice housing on a solderable breadboard. The sensor cables can be plugged and unplugged into sockets on the breadboard. So I can easily exchange the…
a.k.a. longest post title ever 😛 This is the Python code for a NodeMCU v3 running MicroPython 1.19.1. It will measure temperature and humidity at the connected DHT22 with breakout board every 30 seconds, connect to WiFi and publish to a MQTT server.The first code block will be the necessary as simple and clear as…
After expermienting alot with my MQTT server it was pretty polluted with sustained messages and I wanted to get rid of them. The fastest way I got this reliably to work was by deleting the persistence file while the MQTT server was offline. You could delete all or specific topics with a script, too, but…