Coding Like Curiosity – Part 1: Arduino like a Pro

CurioDuino with all three obstacle sensors attached.

When I started this project, I knew almost nothing about Arduino. Today, I’m going to detail what I’ve learned about the Arduino platform over the past month.

Arduino is amazingly easy to get started in. If you know any C or C++, it just gets easier. I got an Uno board, then had a look over the example code and realized just how powerful the platform is. I can interface nearly any type of sensor and immediately start prototyping ideas.

As easy as it is to get started with simple programs (known as sketches to the Arduino community), there is a bit of a learning curve for those lacking electronics experience. For example, I didn’t know how to select the right value resistor for the LED circuits I made in the beginning. Thanks to some helpful online tutorials [0] I was able to understand Ohm’s law and why LEDs need resistors. Another thing that was unclear to me at first was how sensors worked with micro controllers.  Learning this was a lot of fun.

Basically, you can have two types of sensors plugged into an Arduino input: digital or analog. If you’re doing a digital input, you’ve got two choices, 0 (LOW) or 1 (HIGH) [1]. If you’re doing analog, the microcontroller will report from 0 to 1023, depending on how much voltage is being detected [2]. Since the analog output pins on the Arduino can use pulse width modulation (PWM) to output from 0-255, you can use an analog input signal divided by 4 to map an analog input to an analog output [3]. Fun stuff!

One of the best resources I’ve found for learning the details of the Arduino IDE and for basic programming in C++ is Simon Monk’s book “Getting Started with Sketches” [4]. All the basics are covered. Very quick read, only 150 easy pages.

So, now that I’ve got a pretty good hold on Arduino and how it works, the possibilities truly seem infinite. Paring the ideas down into the essentials of what I want to accomplish in this project is one of the most important parts of this process. Planning carefully will save a lot of time later on. I won’t have to rewrite large blocks of code that I deem outside the scope of the project, because I will have all of the important stuff planned.Although, having such a huge amount of potential from a tiny microprocessor is a wonderful feeling.

Here’s what I’m currently planning to use for this project:

1. Arduino Uno R3

2. Pololu Zumo Shield with Robot and Reflectance Array

3. Three Sharp Digital Distance Sensors 5cm

4. Adafruit Bluefruit EZ Link Shield with Stacking Headers

A note on Adafruit’s Bluefruit Shield: I received mine not too long ago, and I experienced a lot of issues using it on a Macbook. Adafruit has acknowledged this issue, and released a software patch [5], but it didn’t fix everything for me. They’re currently working on making an entirely new board that fixes the issue without a software patch. Adafruit’s customer service was amazing on this issue. They refunded the purchase price and let me keep the board just in case I decide I have a use for it.

Thanks for following my progress on this project!

References

0. https://www.sparkfun.com/tutorials/219

1. http://arduino.cc/en/Reference/digitalRead

2. http://arduino.cc/en/Tutorial/AnalogInput

3. http://arduino.cc/en/Tutorial/PWM

4. http://www.amazon.com/Programming-Arduino-Getting-Started-Sketches/dp/0071784225

5. http://forums.adafruit.com/viewtopic.php?f=31&t=47431

Truly Curious: Examining the Mars Science Laboratory Software Development Process

Lego Curiosity Set 

Another project update is currently being drafted, but I wanted to post a quick update with a paper I wrote recently. It details the software development process for the Mars Science Laboratory. I find it truly fascinating, and I hope you do too.

Here’s the link: MSL Software PDF

Coding like Curiosity: Introduction

Mars Rover Curiosity, Right Side View (Photo credit: Wikipedia)

Real-time operating systems have fascinated me since before I even knew what they were. The first real-time application that really made me stop and think was the Curiosity’s (or Mars Science Laboratory’s) software platform. One set of applications are responsible for controlling everything the rover can accomplish. This huge amount of responsibility is handled by a strictly scheduled operating system called a real-time operating system (RTOS). To learn more about how to create critical software for these types of systems, I have decided to adopt some of the software architectural principles, as described by Ben Cichy [0], in a much (MUCH) smaller rover project of my own.

I am going to create a software platform for an Arduino powered robot that will run on an RTOS and be separated into independent modules just like the Curiosity flight software. It will communicate with my laptop wirelessly to provide log details and accept basic commands. The robot itself will be almost entirely autonomous, utilizing an infrared sensor array to detect platform edges and another pair of infrared detectors to avoid obstacles. I’ll be using the Arduino Uno and only have about 32KB for the entire software, including the RTOS libraries. As such, I plan to use the nilRTOS libraries, which were derived from the ChibiOS and are extremely small and lightweight [1].

This blog will be updated as the project progresses. I hope to have it all completed by May 2014. I’ll update with a parts list in the next segment in case any one would like to try a project of their own.

       0. Cichy, B. (2010). The Evolution of the Mars Science Laboratory Flight Software. 2010 Workshop on Spacecraft Flight Software. Lecture conducted from California Institute of Technology. Pasadena, CA

       1.  https://code.google.com/p/rtoslibs/