Under the Bridge
I am not one for micro-management. I’ve always believed that the best results are gained when clear, concise expectations are set, and people are left to use their initiative. Unlike my love life, however, this yacht needs a microcontroller.
How to pick the brains of the operations is always a hotly contested question. Elections, civil wars, even divorces: all the results of contests for control. On this boat, one man, or component, will have control, and the yardarm is ready for mutineers. The only question is who will be at the helm; Captain Arduino, the dashing Italian; Commodore Stix, and his sons Gum and Robo; or even the ever elusive pirate, Mister Handyboard.
Each has his advantages, but each also has the potential the sink this project, Arduino by his hesitance to act, the Stix family because of their obscure mind and Handyboard, because I simply can’t find the bastard son of MIT and lego. To elaborate, a profile of each is necessary.
First off the starting block is the Gumstix family. These are tiny computers running linux, with available bluetooth, and GPS and digital I/0 daughter boards. They are powerful, with 400Mhz cpus, flash memory and SD storage, and ethernet. It’s biggest problem is the OS. Although it’s runs on linux, during a project last year, the team I was in found it very difficult to get a stable buildroot for the gumstix, and when one was found, we could never get all the services to work at once. Cillian Murphy, who had the unenviable task of dealing with the gumstix for that autonomous dirigible project, wrote about some of his woes, and successes on his blog.
Thanks to the experiences I had during the aforementioned Project Hindenburg, I would be very hesitant to use gumstix/robostix. The problems associated with simply setting them up are quite daunting, which could waste valuable time during the project.
Next is the Handyboard. The handyboard was developed by MIT, for a Lego robot contest. It is quite expandable and has an LCD screen, the only option I have investigated which offers such. It runs a 2Mhz Motorola processor, and has 32Kb of battery backed SRAM. It can control four 1A motors and has an add-on board to support servo control.
The biggest advantage of these is that UCD engineers have used them before, and (to continue with my anti-engineer bile) if they can use them…. They have low power consumption, are reliable and, as far as I can gather, the university already has some to hand.
Finally, onto Arduinos. This Italian-made microcontrollers is quite promising. It is much less powerful than the Gumstix, as it is not a micro pc, but is a board based on the ATMEGA168 microcontroller. It has 14 digital I/O pins, 6 of which are capable of Pulse Width Modulation, which is required for controlling servos. It has six analog inputs, a 5V linear regulator and a USB interface. There are available shields aimed towards specific applications, including servo control.
Programming for the Arduino is done in Wiring, a C-like language, and it supplies it’s own IDE in Java, which is available for Linux, Mac and Windows. Loading the program to the board is very quick, over a USB interface, as he Arduino has an inbuilt USB-to-RS232 chip. It has 14KB of available Flash memory to store code.
The fun part, now, conclusions. Years ago, I was told that the fastest way to lose money was to bet on every horse running. Usually it’s best to make a decision and put it into action, and, to paraphrase a popular Japanese children’s cartoon, I choose you, Captain Arduino.
I favour arduinos, for ease of use, lots of i/o and it has enough computational brawn to control the boat.
A close second is the handyboard, which has much of the above. The handyboards have less i/o ports, but do have a track record in the college.
Which will be picked by those in the higher echelons, like the fate of the tanks taken by the pirates of Eyl, has yet to be decided. - D.N.T. (29/10/08)
Once you have made your final decision on the choice of handyboard or arduino I’d like to see another post updating this one that justifies your choice. I believe this should then go directly into your reports.