Open-Source Microcontrollers for Science - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 52

an GNU/Linux 6 ) to take advantage of the open-source paradigm discussed in Chapter 2 , the
Arduino software is truly cross-platform and runs not only on free and open-source GNU/
Linux, but also on Windows and the Macintosh OSX operating systems.
As with most open-source hardware projects, the Arduino quickly began a biological-like
evolution and now there is an extensive Arduino family that is summarized in the next section
along with the other main open-source microcontrollers as of this writing. 7 For some applic-
ations, these more powerful tools may be necessary. For example, the Raspberry Pi 8 is essen-
tially a small very low-cost ($35-40) Linux-based computer only missing peripherals, which
can greatly expand the ability of a project to handle a collection of complex tasks demanding
impressive levels of computation. Here we will primarily focus on the Arduinos because they
are the most established, have the largest user base, and although there will certainly continue
to be rapid evolution in the Arduino family, by understanding the basics you will also be able
to work with the more advanced boards as they are developed.
This chapter will take you through a relatively complex example project for creating an en-
vironmental chamber. The environmental chamber is an ambitious first project for someone
who does not have any experience with microcontrollers. However, if you follow the steps
outlined in Sections 4.3 - 4.5 , you will have a functional environmental chamber when you are
done. However, if you want to alter, improve or build on the basic setup described, you will
need to have an understanding of C++ and a more in-depth understanding of microcontrollers.
At the end of this chapter, several topics were recommended for providing a irm foundation
in Arduino control; however, Adafruit has excellent tutorial library, which should be useful
for geting anyone started. 9
4.2 The Open-Source Microcontroller Family
There are more than 16 Arduino-based open-source microcontroller boards. The microcon-
trollers that would be of most use to the science community are summarized in Table 4.1 in-
cluding their approximate cost, special features, processor, process speed, analog and digital
pins, memory, programming language, programmer, and how to expand their capabilities. In
the expansion section, the term “shield” refers to interchangeable add-on modules. This is an
extremely important feature made possible by the standard way that connectors are exposed
on Arduino boards, allowing the CPU board to be connected to a variety of known shields
to tackle specific tasks. Some shields communicate with the Arduino board directly over vari-
ous pins, but many shields are individually addressable via an I²C serial bus, allowing many
shields to be stacked and used in parallel. For a list of available Arduino shields, see the Ar-
duino shield list maintained by Jonathan Oxer. 10