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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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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A self-hosted MQTT environment for Internet of Things – Part 2

In the second post in this series, I will setup two ESP8266 microcontrollers with MQTT publishing through a Raspberry Pi-hosted Mosquitto broker. The idea is that the microcontrollers will send sensor data (like temperatures or other events) that one or several MQTT subscribers can act on.

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Exploring Adafruit IO

Adafruit hosts a cloud service,, where you can upload data from your devices and also subscribe to data from other devices. The service is currently in beta, but you can sign up for a free account to test it. The data is stored in “feeds” and you can configure your own dashboards for viewing the data. There are two API:s available. One is REST-based and the other follows the publish/subscribe pattern of MQTT. In this post I will try both alternatives.

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A Lego robot car with Arduino and servo motors

With an Arduino and some servos lying around, I find it hard not to try out something robot-like. An obstacle-avoiding mini car is probably one of the easiest projects to get started with and as our house is abundant with Lego, the building blocks for the construction are readily available.

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Arduino to Raspberry wireless communication – some improvements

In my previous post, I experimented with sending measurements values from an Arduino UNO to a Raspberry Pi via a 433 MHz radio protocol. After testing the setup for a few days, I decided to make some improvements:

  • Add an additional sensor for measuring outdoor temperatures. Now there will be four different sensor values transmitted from the Arduino to the Raspberry Pi.
  • Add the possibility to send float values for more precision and, for adopting to the Swedish climate, allow negative values.
  • On the receiver side (the Raspberry Pi), add storage of the values to a csv file so that the measurements can be visualized in graphs with Excel or a similar application.
  • Improve the noise tolerance.

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