Introduction

Background:
This has been an on-going project of mine. It all started when I moved to Cambridge, MA for grad school. My apartment has really old heating and no central air, so naturally the climate inside varies pretty substantially from hour to hour.

Question:
Wouldn't it be cool if I could put a bunch of sensors around my room to get information about how the temperature and humidity change in different locations over time?

Answer:
IT WOULD BE AWESOME!
 
Implementation:

1. Arduino Programming:
   1. Arduino is super convenient to use as the basis for this project for a few reasons:
      1. Many open-souce libraries exist for it
      2. The boards are super cheap
      3. There are a lot of cheap Arduino-compatible sensors and actuators out there.
2. Wifi Connectivity:
   1. The abillity for my boards to be connected to the internet is crutial
      1. There are a few cheap wifi modules that are Arduino compatible. In fact there are cheap development boards that include an MCU connected to a built-in wifi module, and work with the arduino IDE (ESP8266 NodeMCU 12e). More on this in a future post.
      2. Wifi means I can build a modular sensor network. Each node can transmit data wirelessly (i.e. the only wire input is power).
3. Data Storage and Accessibility 
   1. The final piece of the puzzle is a place to store all of this sensor data in a place where it will be useful. Interestingly, Mathworks has already developed a web service that allows users to dump data to thier servers.
      1. ThingSpeak.com is a free data hosting website designed specifically for IoT projects.
      2. There are a few free Android apps that allow users to display data from ThingSpeak Channels.
      3. There is an arduino library that reads and writes to ThingSpeak.
      4. The ThingSpeak API is open source and well documented.
      5. Since it's owned by Mathworks (which owns MATLAB), you can easily create custom Matlab scripts to analyze data. Better yet, the scripts are stored and run on thier server, and can be set to run in response to data being pushed!