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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RCSwitch revisited – control RC outlets with a web app

In two previous posts, I used the RCSwitch and pi-switch libraries for communication between an Arduino Uno and a Raspberry Pi. I touched briefly on the main purpose with these libraries – to control RC outlets. In this post I will dig deeper and decode the RC signals so that the remote control can be replaced by a web app running on any browser-enabled device.

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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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Getting started with Windows 10 IoT

Now that I have a Raspberry at my disposal, it is possible to install Windows 10 IoT on it and explore what Microsoft have made available for the Pi. Why would I run Windows 10 IoT on a Raspberry? I don’t know yet, but as Windows 10 IoT is free, let’s try it out!

For my experiments I used this setup:

  • Windows 10 with Visual Studio 2015
  • Windows IoT version 10.0.10586.0

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Raspberry Pi & PS2 EyeToy

Last week I finally got around and bought my first Raspberry Pi. Getting it up and running with Raspbian via Noobs was a breeze and after playing around with the OS and Python for a while I decided to get some real use out of this little machine. My first experiment aimed at a home security camera. As I did not want to invest in additional hardware, I used what I could find in the household’s scrap heap – in this case a no-longer-in-active-use PS2 EyeToy camera.
My first intention was to use SimpleCV and Python to take regular snapshots and let a rudimentary WebAPI expose the latest image to the outside world. The code for this would be very simple and easy to extend with additional features. But, this experiment failed as I could not get a proper driver for the EyeToy working with SimpleCV.

My next test was to use an open-source tool for talking to the EyeToy. I tested Motion and it connected right away with the camera. Motion is a very powerful motion detection tool with tons of configuration options. The features that I was interested in were available:

  • Take a photo at a regular interval
  • Expose the photo via a web interface
  • Security options for the web interface

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