InfluxDB and Grafana for sensor time series

I’ve started using InfluxDB for storing my sensor data as time series. The main reason for this is that it allows me to use Grafana for analyzing the data. This blog post is an introduction to my setup with these tools on a Raspberry Pi.

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Home Assistant – integrating RESTful switches

I have started integrating my IoT-devices and services with the Home Assistant platform. See my previous post for details on getting started with Home Assistant and subscribing to MQTT messages:

Home Assistant – getting started and using MQTT sensors

My next attempt is to configure RESTful switches in HA for interacting with an existing web service that I use for controlling 433 MHz outlets. I will also add automation rules for the switches and test the voice command in Home Assistant.

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Home Assistant – getting started and using MQTT sensors

I’ve been searching for an easy-to-get-started home automation platform that can be extended and customized as my needs grow. After struggling with OpenHAB, Domoticz and Freedomotic, I’ve found Home Assistant to be a much better fit for me. My main requirements are that the system should be open-source, have good tutorials & documentation, work well on a Raspberry Pi and be extensible for my likely future needs. I will spend this and a few upcoming posts with my Home Assistant experiments.

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Monitoring CPU temperatures on a Raspberry Pi with MQTT

Recently I’ve had problems with my Raspberry Pi 3 overheating though I use a heat sink for the processor and have a very modest load on the machine. When the RPi is in this state, it shows a thermometer warning icon and it is not possible to login. As I can not access the machine, it is hard to investigate the cause of the heat problem (if a process has gone totally wild e.g.). The only way to resolve this is to do a hard reboot (then the temperature goes down again).

To investigate this further, I want to monitor the CPU temperature without accessing the RPi via ssh or a direct login. My idea is to let the RPi gather board temperature values regularly and then publish these via MQTT. An MQTT subscriber will see to that the measurements are propagated to a cloud service so that I can monitor the values in an external application. With IFTTT I can add alerts on the measurements (e.g. when the CPU temperature goes over 60 C, an e-mail should be sent to me). This way I will be notified before the temperature/load gets too high and I will hopefully be able to intercept the problem by logging in to the machine before it locks up.

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The MicroPython Lego Bot

In the quest for getting my kids interested in coding, I’ve decided to make them a message controlled bot car with Lego bricks and an ESP8266 board. The idea is to have an environment where we can jointly program a sequence of actions that can be sent via WiFi to the bot for execution. With this setup we can make challenges like creating the optimal sequence for navigating through a maze or simply try out crazy movements & mayhem just for the fun of it. Hopefully, having an assignment were you need to connect an abstraction like a sequence of symbols with a physical object will ignite a spark of interest for electronics and the basics of programming.

This post describes the first part of this project. I will use Lego bricks and some servos to build a car bot and mount an ESP8266 board loaded with MicroPython. To begin with, the bot will be controlled via WiFi through MicroPython’s WebREPL.

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A sensor monitor with OLED in MicroPython

I have different sensor nodes at home that publish measurements at regular intervals to a Raspberry Pi. The data is stored on the RPi and in a cloud service and can be viewed with various applications. As my most common use case is to view the latest value of a particular sensor, I would like to have a mounted low-powered display in the kitchen to show the latest values from my sensors.

In this post I will show how I have used an Adafruit Feather Huzzah and a FeatherWing OLED that monitors the latest messages from my sensors. To get out of my normal comfort zone (Arduino IDE with C/C++), I will use MicroPython for the implementation.

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Preparing the remote control app for Christmas

Winter is soon to arrive in Sweden and the amount of daylight is decreasing every day. Thus it’s time to set up some extra light sources indoors and outdoors. I have been using my web app for remote controlled outlets (link) for some months now, but with the additional light sources needed for this time of year, I have to extend the application. As Sweden goes into the dark season I would also like to have an on/off schedule for some of the lights so that they are turned on/off automatically according to a set of specified events.

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