Blynk, PlatformIO and ESP32

Blynk is an IoT-platform that consists of a Blynk server, custom projects within an iOS/Android mobile app and custom hardware IoT-nodes (Arduinos etc) using a Blynk library. The mobile app communicates with the hardware via the Blynk server and you can use the mobile interface for displaying sensor data from the hardware nodes or control actuators on the nodes.

You can use the cloud version of the Blynk server or host your own instance. In this post, I will show how I have setup a Blynk server on a Raspberry Pi and how I am using it for mobile communication with an ESP32 board that is developed with PlatformIO for Atom.

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The Sensor433 library and Geeetech transmitters and receivers

As I use 433MHz transmitters for sending sensor data from many of my IoT-nodes, I have made a re-usable Arduino library for this purpose. The transmitted sensor data is picked up by one single receiver (an ESP8266 board) that converts the values to MQTT messages on my local network. In this post I will describe this library, my setup and also a set of new 433MHz transmitters and receivers that I have upgraded to.

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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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Radio chirp data incorporated in an MQTT environment

Internet-of-things does not require that every device has to be directly connected to the Internet. The complexity and possible security issues with every sensor having its own IP address would in fact be overwhelming. A better approach would be to use more light-weight protocols for the sensor and actuator data and locally aggregate and filter these data at common points before making them available on the Internet. In this post I will describe a theory and implementation of transmitting small radio chirp messages from an Arduino Pro mini and then receive these data on a Raspberry Pi for transformation to MQTT messages for the Internet.

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Processing and Arduino

Processing is an open-source IDE with a Java-based programming language that is aimed at lowering the learning threshold for interactive graphics creation. It can be used for teaching programming, making prototypes, creating art experiments or just generating crazy visual stuff in general. The community is very active and there are tons of useful contributed libraries. Wiring and the Arduino IDE are spin-offs from Processing and there are many cool things happening in the JavaScript version of Processing, p5.js (more about this in an upcoming post).

In this post I will connect a Processing sketch with an Arduino for the purpose of visualizing the input and output pins of the hardware board with graphics in Processing.

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