Where I live there aren’t really any options for electronics shopping,
so I was resigned to do it mostly through mail order. Fortunately I
discovered that Kjell & Co., which is probably the closest
thing to Radio Shack we have in Sweden, not only carries a lot of
Arduino stuff, but also has an shop in the next town over (Luleå,
about 50km away).
So I got myself a soldering station, some lead-free solder some
sensors and grab bag of diodes, resistors and cables to play with. It
must be something like 25 years since I last had a soldering iron in
my hands, but putting the T-cobbler together I all just
came back to me. Even the smell was exactly as I remembered it.
I had some problems getting the DHT11 sensor up and
running. All the examples I could find had a four-legged sensor, but
mine came pre-mounted on a board with only three. Also, the
configuration of the legs had been switched around. That one took some
The DS18B20 however, just plain refused to show up as a
/sys/bus/w1/devices. I tried everything: reflashed the SD
card, checked the kernel messages, double-checked my connections
(twice), moved things around on the bread board in case there was a
break (which incidently there is; the vertical strips break in the
middle, but this didn’t affect my wiring) and tried every combination
of power and GND I could find on the breakout board in case I had done
a bad soldering job (which I hadn’t). I did countless reboots. Still
I had just about written that sensor off when I discovered that the
pullup resistor I’d used wasn’t yellow-purple-red as specified, but
yellow-purple-yellow. 470K instead of 4.7K. Oops.
Hardware is hard.