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battery chainsaw birthday
Tuesday, February 16 2016
Snow had fallen for much of the night, though it never accumulated beyond an inch or two. By this morning, the snow had turned to rain. Temperatures climbed into the upper 50s by this afternoon, so I opened a garage door to let the warm air in. This might have sped the thawing of my urinal system, which had been frozen for two whole days. Something about the snow followed quickly by rain exposed a network of mouse or vole trails that had been excavated under the snow. Here you can see one running along the side of the driveway:
Today was my 48th birthday, and Gretchen did the usual things to make it special, starting in the morning with a completely homemade pizza and a french press full of coffee.
Weeks ago, we'd established that I wanted a much more powerful battery-powered chainsaw as my birthday present. I'd requested the 80 volt 18 inch Kobalt chainsaw, mostly because I intend to be hard on it, and it's likely I will need to take advantage of its five year warranty. GreenWorks is the pioneer of battery-powered chainsaws, but I've had bad luck tracking down a way to get my GreenWorks saw(s) serviced and have been forced to do the servicing myself. The great thing about Kobalt is that it is the Lowes store brand, so I know exactly where to go if and when the troubles begin. Gretchen likes to "get" me by telling me straight-faced lies about various trivial things in hopes that I will believe her. She'd done this with the Kobalt chainsaw, saying it probably wouldn't be arriving in time for my birthday. This struck me as odd, since I thought one could just be picked up at Lowes, but it seemed plausible. That supplied the small amount of surprise related to the present when she plopped it down beside me this morning. I immediately inserted the battery and fired it up. It's louder and heavier than my ten inch GreenWorks saw, but it seems a lot more capable.
Gretchen worked her very last day at Ulster Literacy Center today, passing the baton to a new person who will be running the program she started that provides literacy coarses in the Ulster County Jail. She hadn't been enjoying the job for most of her time doing it and has decided to try organizing and running poetry workshops instead. Who says a master's degree in poetry from Sarah Lawrence is completely worthless?
Meanwhile, I attempted yet again the failed project from yesterday of ascertaining which pins need to be connected between a Raspberry Pi and a 5 inch HDMI touchscreen. This time I double the length of the jumper wires and dragged over a floor lamp to provide better illumination as I worked. Eventually I was able to eliminate large swaths of interconnections, including all the wires of the I2C bus and a bunch of the PX wires. In the end, the only wires necessary were ground, +5v, possibly +3.3v, all the SPI wires except CE0, and P6.
Once I'd opened up the Raspberry Pi's I2C bus, I decided to see if I could use it to communicate with an ATTiny85-based I2C Slave that reads temperature data from AmbientWeather F007TH probes transmitting at 433MHZ. I have one such device already hidden inside my "weather station probe," so I build another from scratch, flashing my custom firmware onto a ATTiny85 and then building a little circuit board allowing it to connect to a wireless receiver and an I2C bus. Once I had it all together, I connected it to the Raspberry Pi and then Googled how best to do I2C bus in the Raspberry Pi universe. I had to install some libraries and what not and then, ultimately, write a short program in Python, a programming language I knew almost nothing about (but which is sort of the house language of the Raspberry Pi). I was immediately skeptical of its lack of line terminators and its semantic use of indentation, but soon enough I had a program working that did pretty much what a demo script I'd written for Arduino had done, but in this case it was doing it on a Raspberry Pi as viewed through a terminal window across a network. The Arduino code had been very reliable, but in Python on a Raspberry Pi, the I2C-data-slurping code would occasionally encounter an I/O error, perhaps because of the imprecise timing characteristics of a multiuser/multithread operating system. So I had to include code to trap such errors. Here it is, my first Python program:
Usually a project of this level of complexity has problems that need to be debugged, but this one only had one, and it was an odd one: the 32 byte buffer inside the ATTiny85 (or perhaps in the Raspberry Pi) seemed to be misaligned such that it would start reading somewhere in the middle, wrap around to the beginning, and then stop again somewhere near the middle. This skewed the location of temperature probe data in the 32 byte packets received. Fixing the problem was easy; all I had to do was briefly ground the reset pin on the ATTiny85.
This evening, my birthday celebration took place at La Florentina, the lovely little Italian restaurant with unusual Syrian-influenced dishes such as sformato (aka "purple pie"). There ended up being eleven of us, and we had the front room all to ourselves. For some reason, the genders segregated themselves, with the women mostly at one table at the southeast end, most of the men (including me) in the middle, and then Gretchen, Eva, and Sandor at the northeast end. Gretchen's plan of selecting a place to seat after everyone else sat down sort of backfired, and she ended up not sitting next to the people she would have preferred to sit next to. As for presents, I got three more-or-less. Michæl (of Carrie and Michæl) gave me a piece of plaster he'd cast inside a woodpecker hole. He's an artist and it was art. David (of Susan and David) gave me a convenient little toolbox, because you can never have too many of those. And Ray and Nancy got me a big newsprint sketch pad and live model studio sessions, which I think they will be attending with me.
Gretchen had made a bunch of vegan cupcakes for the birthday celebrants who, unlike me, enjoy non-savory food after filling their guts with savory food. She gave several to the La Florentina staff, and the Syrian co-owner was so impressed he expressed interest in selling Gretchen's cupcakes in the restaurant.
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