Sub Ubi

The Wikipedia, the source of all knowledge likely but questionable, has this to say regarding the word walkabout:

Walkabout refers to the belief of non-indigenous Australians that Aborigines were prone to “go walkabout” (a pidgin or perhaps quasi-pidgin expression) meaning that they would stop doing their jobs and wander through the bush for weeks at a time.

This has lead to a jocular modern usage, whereby someone who has unexpectedly wandered off to destination uncertain is said to have ‘gone walkabout’. It can also apply to a missing item, for example, “Have you seen my stapler, Doreen? It’s gone walkabout again.”

“Whereby someone who has unexpectedly wandered off to destination uncertain.” I like this a lot; my intention is to wander off to destinations uncertain with Greenfoot, and begin exploring how we can use this wonderful piece of software for teaching and learning Java. And, if I have anything to say about it, we’ll certainly have some fun along the way.

Porting to bare hardware is slightly more difficult than I thought it would be.

The Transterpreter recompiles to new targets with little or no effort; it’s just not a big deal. The VM is written in a subset of ANSI C that ports well from one machine to another. However, running on bare hardware means that you must first initialize the hardware.

This has been my biggest battle with the Tmote Sky. I’m not particularly well versed at reading datasheets (PDF) for hardware boards, nor does everything in the MSP430 processor specification (PDF) make sense to me the first (or second, or sometimes the third) time through. I’ve spent a fair amount of time in the last few days just reading the lowest-level sources for TinyOS, which has taught me a great deal about how they initialize the MSP430 (and therefore, the Tmote Sky).

For example, it took some time to discover the LED initialization sequence:

#define INIT_LEDS()  P5DIR = 0x70 ; P5OUT = 0x70;

And, I’m not even sure about my setting of the P5OUT register. Certainly, those register settings ignore everything else on port 5.

The serial communications took longer; I have to admit, there’s still some things going on that I don’t fully understand, as my initial explorations in this area were almost the same. Granted, one bit might make a difference in this case:

#define INIT_SERIAL()
  P3SEL |= 0xC0;
  U1CTL = SWRST; U1CTL |= CHAR; U1CTL = SWRST;
  U1CTL |= CHAR; U1TCTL &= ~(SSEL_0 | SSEL_1 | SSEL_2 | SSEL_3);
  U1TCTL |= SSEL_ACLK;  U1BR0 = 0x03; U1BR1 = 0x00;
  U1MCTL = 0x4A; ME2 &= ~USPIE1;
  ME2 |= (UTXE1 | URXE1); U1CTL &= ~SWRST;

That code is heavily based on some of the hardware initialization code in TinyOS.

This is an important start, and not bad for three days of work. It’s not as quick as I thought it would be… but it isn’t terribly slow, either. Once I have the hardware initialization sequence done (the biggest pieces left are the flash and the radio), “porting” the Transterpreter is a piece of cake. That is, binding external channels to these interfaces isn’t the hard part—it’s just getting the mote to come to life with everything ready to go that is the trick!

(Of course, learning how to turn these devices on and off is going to be another challenge…)

I’ll be in London this evening, and on my way to LA tomorrow. It’s an 11-hour flight that lasts 3 hours on the clock. Absolutely wacky. A week in LA, two weeks in Cleveland, and another week in LA.

I should have good ‘net access—so contacting me through any of the six bizillion ways people can contact me is probably all good. I’ll try and forward my SkypeIn number somewhere physically close to me while travelling, even.

Jadud you goober, “The Pirates who Don’t Do Anything” is a decade-old
song from the very popular Veggie Tales series. Reliant K is covering
the song, but they surely didn’t write it.

http://www.bigidea.com/music/singalongs/pirates_boatload.htm

http://www.stlyrics.com/songs/v/veggietales4708/werethepirateswhodontdoanything209666.html

There you have it. Dave has spoken.

we are the pirates we don’t do anything
we just stay at home, and lie around
and if you ask us, to do anything
we’ll just tell you, we don’t do anything

Somewhere out there is a band called “Reliant K”. They wrote a song called “We are the pirates who don’t do anything.” That, I think, is excellent. The lyrics are quite good.

Huh. A bit of searching yields that they are a Christian rock band from Canton, Ohio. Who knew that Christians could be pirates? Granted, my office-mate Christian occasionally dresses up like a pirate, and even talked like one at a conference. So, it just goes to show, you cannot judge Christians or pirates, even when they are one and the same.

In a slightly different vein, I liked this description of software developers as either Assholes or Morons. Flying in the face of our vaguely Christian theme this morning, it seems like there are no Angels in the software development world. It seems like software developers and pirates need to go on an adventure together.

Update: See next post for corrections.

It feels sooo good to be home.

The last two weeks were intense. A week at DIKU, where we presented a lecture on CSP and robotics to the Extreme Multiprogramming course taught by Brian Vinter. Both Christian and I enjoyed ourselves more than during previous talks/conferences we’ve attended. Why? Because we had our shit together before we left, instead of trying to make everything perfect up until the last moment. (Granted, this just means we spent the week previous making everything perfect… but hey, what can you do?) I certainly enjoyed my visit to DIKU, the students were great, and Copenhagen was a neat city. I’ll have to write about the exclusive tours of several Danish castles that I was granted at some point.

Friday of last week was dominated by a research group meeting and two additional meetings, one of which will give birth to a new weblog that I’m really excited about. All I can say is that it involves Greenfoot… but I suppose that mostly gives it away. More here when that time comes.

Saturday last was an all-day, fix-and-tweak on the dissertation. Granted, some new literature was included, a few new pages were added, and a lot of formatting was carried out to produce a final version. That felt good, but it still hasn’t sunk in.

Sunday we released RoboDeb006. This is a great, stable environment for exploring the Player/Stage simulation environment using occam-pi. You can probably use it with other languages as well, but we’re quite keen on the notion of safe concurrency and robotics. It’s really schweet. It’s time to start cranking on a paper on this, and get that out the door ASAP. Our last presentation made it clear to us that the technology is mature, and the ideas sound.

And this week was spent bouncing between Glasgow and St. Andrews, working with my counterparts on the DIAS project. In particular, I was keen (as someone working at the OS/VM level) to talk to RA-Glasgow about radios (which live below the OS) and RA-St.A (about code generation). This was critical for determining future direction of the OS-layer. Actionable is that I have in hand several Tmote Skys, which are a generic, but useful, sensor mote package. I’ll be porting the Transterpreter to these, and see if our claims about the value of concurrency in the small hold up in practice.

And now I’m home again. There’s stories to tell in there (for example, “Tales from the Youth Hostile from Hell”), but for the moment, it’s just nice to be sipping Spitfire and grooving to tunes in the comfort of my little, overpriced apartment in Canterbury. Next week, I get to catch up with Ralph (former housemate), and the week after I head for CalTech, and will be kicking it with Robin (former housemate). Busy, yes, but at least the intensity drops off a bit.

Our virtual machine for exploring occam (running on the Transterpreter) as a massively concurrent control language for robotics platforms is now available for download.

See the RoboDeb Quickstart Guide for more information. If you download it and start playing with it, please drop me a note (matt at transterpreter dot org) and ask to be put on the mailing list. We want to hear from users regarding their explorations and experiences!

For those interested in computer science education research (generally) and novice compilation behavior (specifically), I’ve placed a PDF of my dissertation (as it will be submitted for examination) online. It is titled An exploration of novice compilation behaviour in BlueJ. This version will eventually be replaced with the final, defended-and-approved version, which I expect will also include acknowledgments.

I’m off to Scotland for a week, and no, it isn’t for holiday time. If you want to reach me, I recommend using Gmail or SMS.

I received my dissertation back from my supervisor Friday. If I wasn’t heading out to Denmark tomorrow, I’d submit on Monday. As it stands, barring disaster, I will submit my dissertation in six days; Christian and I will give our talk, the workshop, I’ll return, make the recommended edits, and I’m done.

Well, done-but-not-done, as there is still the small matter of the defense.

But still. Six… days…