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Hammer of the Gods
Saturday, March 12 2011
Yesterday before Gretchen and I left for Rosendale, a thought occurred to me about the master and slave Atmegas in the solar controller and why I was having such a difficult time making a system allowing the master to synchronously request data from the slave. The documentation of "Wire," the library responsible for I2C communication in Atmegas, is spotty and example-free, and I've been able to find no examples online of anyone sending requests from a master for the return of specific data from a slave. Part of the problem I'd been having lay in my assumptions about how the Wire.onRequest handler works. I'd assumed that this handler could be used to retrieve data sent by the master (since other I2C devices seemed to work this way). But it turns out that this is not the case. To send data to a slave as part of a synchronous request followed by a returned result, the slave can only retrieve the request data using the onReceive method. On the slave side, this means that the onReceive handler has to take the data passed to it, process it however it needs to be processed, and put the results into global variables that can then be queried in the onRequest handler.
I stayed up late working on this problem but wasn't having much luck solving it. This morning I got up early and continued to work on it, trying a few things that occurred to me after I'd awaken (but before I'd gotten out bed). The main problem with debugging complicated protocols involving a master and a slave in a live system is that I had to keep running back and forth between the laboratory (where I was doing the coding and looking at the results of my tests) and the basement (where the controller is installed). This was only to throw the switch that connects the serial cable to the laboratory so it was either attached to the master or two the slave. I should have just unplugged the controller's several cables and brought it upstairs to work on, but I kept thinking I'd nearly solved the problem. Between my laboratory and the basement are 29 steps and I must have gone up and down those stairs at least twenty times before I came upon a solution that was nearly good enough. No matter what I did, I couldn't make synchronous communication completely error-free, but I managed to come close by sending three copies of all the data being requested and testing to see if they all matched. Those as frustrated by this problem as I have been are welcome to download my code, which includes this master-slave synchronous communication (along with many other things).
Later I tried to hook up a relay to bypass the hot water tank's thermostat during the summer (allowing the controller to determine cutoff decisions digitally), but I couldn't get it working for some reason [it turned out that the ULN2003 I was using had been damaged by a wiring mixup early in the installation, but I wouldn't know that for another day]. While I was doing this, the controller crashed during the change of one of its high-voltage inputs, and I realized I'd have to install capacitors or something to absorb voltage spikes. While I had the controller torn apart to do that, I upgraded the I2C EEPROM sockets to support 128 kilobyte 24LC1025s, the A2 pins of which must be tied to five volts in order to be able to use their full capacity.
This evening Gretchen and I drove up to Albany to see a Led Zepplin tribute band called Hammer of the Gods. She'd bought tickets for both of us as a birthday present for me, though she was clearly more excited about it than I was. Don't get me wrong, I love Led Zepplin. But seeing someone trying to impersonate them is something else entirely. I expected the experience to be enjoyable mostly at the level of camp. Still, it was an excuse to get out of the house and have dinner somewhere new. We'd narrowed down our restaurant choice between a pizza place and a Mexican place, and before we left Gretchen had decided El Loco, the Mexican place, seemed best-suited to our needs. So that was our first destination.
El Loco was in the Lark Street neighborhood which we used to visit specifically for its Indian restaurants. Now, though, we have a perfectly good Indian restaurant in Kingston and there don't appear to be any Indian restaurants on Lark Street. (One of the places we used to go to now claims to be an Irish pub.)
While waiting for our seat in El Loco, we walked around a couple blocks, marveling at the beautiful rowhouse architecture. Tonight might well have been the first warmish Saturday night of the year in Albany, and falling as it did on the weekend between Mardi Gras and St. Patrick's day, all the young adults had filled the streets in pursuit of one drunken goal: to wake up beside a stranger. As I saw all these people with their green shirts and Mardi Gras beads, I had to ask myself: how do the Irish (who are largely Catholic) justify their St. Patrick's Day revelry, given that it nearly always takes place during Lent? (As with all questions, Wikipedia answers.)
El Loco smells vaguely of body odor inside, something Gretchen had initially attributed to one of the people in front of us waiting for a table. But that's okay; it was packed with people, some of whom probably didn't smell too good. We ended up at a tiny seat back by the bathroom. I ordered the tofu fajitas, and when they came out they were pretty much like the chicken fajitas you can order at Chili's, and I mean that in a good way. I really don't understand why people feel the need to eat actual chicken when tofu can be made to serve the same purpose (although I have to admit I've yet to find a substitute for fried chicken thighs, especially the kind with just enough kidney attached to taste like an unflushable urinal, but I mean that in a good way).
The Led Zepplin tribute band would be performing in the large hall of the Egg, Albany's space-age performance venue. The Egg is part of Albany's Empire State Plaza, one of those modernist tower-in-park redevelopments so popular in the 1960s (and so frequently bemoaned by James Howard Kunstler). This was within easy walking distance of Lark Street, so we went there as pedestrians. I've been reading Kunstler's The Geography of Nowhere, so as we approached I had all Kunstler's arguments in my head. Most of these were architectural. A building is supposed to tell you how to enter it by its design, but modernist buildings present themselves as a puzzle. How does one enter the Egg, an ovoid blob on a stalk? There was no queue of people to tell us how, and certainly no grand entrance. We entered through a door that looked like it should have been locked and jumped into an elevator with an aging roadie in a Led Zepplin teeshirt. But eventually we were digorged into the space where people drank beer and wine in anticipation of the evening. It was an intersting space, with curved, sloping, windowless walls that read "underground" far more than "inside the cap of a concrete mushroom." Gretchen was grooving on the modern architecture far more than I was, cautioned as I'd been by Kunstler about its longterm costs.
The people who had turned out to see a Led Zepplin tribute band were pretty much the demographic you'd expect: lots of middle-aged guys and women with haircuts frozen in the early-to-mid-1980s (a telltale indication of when they'd lost their virginities). There were also a smattering of younger people there, not necessarily with companions their own age. One young woman wore a skirt perhaps six inches long and a pair of hooker boots with stilleto heels.
Because tonight's main act was a tribute band, there was no opening act (who wants to be an opening act for a tribute band?). Our Led Zepplin sound-alikes took the stage, looking a lot like Led Zepplin circa 1974. The drummer even wore a mustache, unfashionable though it is in this day and age. I found the performance of the opening song (I believe it was "Good Times Bad Times") strangely wooden, and I began to wonder how miserable my evening was going to be. The "Robert Plant" had no charisma at all, though he had a competent voice and could simulate rockstar swagger, but it looked like an act. Gretchen thought his antics looked "gay," and by that she meant that she thought he was probably a man who was interested in other men in a sexual way. Usually when I see live rock and roll, it's bands performing their own music, their children. They're fully invested in it and at times it can be as if they are channeling a force much greater than themselves. There was to be none of that tonight.
The band seemed to warm up over the course of their subsequent songs. The person on stage with the most charisma seemed to be the bass player, who wore a ironed-straight auburn wig to make him look like John Paul Jones. He kept a straight face as he plowed his way through the bass run parts, which are essential to any Led Zepplin song. He was also quite good with both keyboards and mandolin. As for the Jimmy-Page-wigged guitarist, his playing seemed a bit sloppy at times, and the guy at the soundboard mixed him too quiet during "Stairway to Heaven." His face from his chin-up looked quite Pagelike, but from his neck down he looked more like a troll. I can't really think what to write about the curly wig on his head, except that it concealed parts of his face that were less Pageque.
As for the drummer, the John Bonham, he was amazing. His version of Moby Dick went on long enough to give the rest of the band time to drink an entire beer and queue up for leisurely shits in one backstage restroom. (I have no idea how many the Egg has backstage.)
It would have been nice to suspend disbelief and to imagine that Thunder of the Gods actually was Led Zepplin, but we kept being reminded that we were paying tribute. The screensaver lightshow behind the band would cut to an image of an album cover and then to a tracklist, focusing on the name of the song about to be played. Really? Did we have to have everything spelled out so explicitly? I'm not a huge Zep head, but I know the songs and it felt patronizing. I also found it absurd during "Stairway to Heaven" when, after singing "...and the forests will echo with laughter," the Robert Plant impressionist asked of the crowd, "Does anyone remember laughter?" Yes, fake Robert Plant dude, I remember that Youtube clip of Robert Plant, and it was stupid when he asked that question, so imagine how stupid it is when you ask that question?
The show went on for nearly three hours. By the end there I kept wanting it to be their last song, but at least Gretchen was enjoying herself.
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