In determining a method to create a distributed sensor network I decided to test the idea of taking some old hardware to use it as a remote server to communicate with Arduinos. The basic idea is to have a server that communicates with the Arduinos and sends the data to a central monitoring process over the network. As long as you have a network connection to the server, you can add as many Arduinos as the server can handle to monitor or control whatever it is you are trying to accomplish.The motivation for this investigation revolved around Energy Management.
This article is not meant to be a step by step procedure, simply because there are many variables in each of our situations. Mainly this is a guide to how to accomplish the task with a conceptual basis that will lead you to discover some solutions that are needed for your application. It is more of a framework with some details and references.
The Arduino Server will be focused on Linux. I guess it is possible to consider windows, but I have not been able to find the same capabilities easily and I am not sure it is even worth investigating, given the ease and flexibility of linux in this application. The central monitoring computers can be any OS that is capable of communicating to network TCP ports or file transfer, which is pretty much anything.
- You are familiar with the Linux command line
- You understand basic text file configuration methods
- You are familiar with serial communications in Linux
- You are able to manipulate computer BIOS settings
The idea is that you are able to find any old server that you may have laying around and put it to use and save you money. The hardware requirements are very little, as long as you have about 256k in memory. It may be possible to have less, but that is where I decided to draw the line. The processor is mostly irrelevant, because just about any processor you have laying around will most likely be able to manage the light load we are creating. I will not be testing it, but it may be possible to go as far back as a 386. The hardware configuration that I am using is a 1.2MHz pentium with 256k in memory, which actually works very well even in full GUI mode. You should also be able to find this type of computer laying around in many junk piles at a computer swap.
After a significant search and years of playing around with small linux distributions, I have fallen on upon Tiny Core Linux. It is amazing. With this distribution you can breath life into old computers you thought were long useless. It has a full GUI and is quite capable of many tasks. With a quick download you can be up and running in no time. What really sealed the deal for me was the fact that I could change all the characteristics of this OS with ease and quickly. After fiddling around with many other linux distros for hours or even days, I was making progress with Tiny Core literally in minutes. I'm completely sold on this idea and concept and while many have created small distributions, this concept is masterful in my eyes and far better than any other that I have tried.
With Tiny Core you have these boot options: HD,CD,USB,PXE. I am focusing on PXE (Network Booting), because to me this is the best way to manage old computers that tend to die. I can pretty much find any old computer with net boot capability and just plug it in and off we go with very little work. The CD and USB are similar in this capability, but not nearly as fast on booting up. The HD being the least flexible of all options, but may not be too bad if you use an IDE to SD converter, which I have not tried yet, but they look interesting.