For flashing the bootloader, I actually installed a 4-pin 2mm pitch header on the left side of the unit. It was a very tight fit - I expected to find a little more free space inside the casing but as it turned out it was a challenge just to route wires from the microcontroller pins to the header and still get everything back into the case. (This has given me a real appreciation for the elegance of the product's design, though!)
Now that I've flashed the bootloader, though, the SPI header feels a bit like a liability. In retrospect I probably should have just connected to the exposed vias. Now that the bootloader's on I may rewire the pin header to some of the unused I/O pins instead.
My first little test project was to monitor an analog temperature sensor - I've got a soda dispenser at home, and it uses a big aluminium block with metal pipes embedded in it to chill the water and soda syrup prior to carbonation and mixing. (Warm soda loses its carbonation too easily, goes flat during dispensing...) Anyway, the system had an ice maker that was used to chill the plate, and that broke down, so I want to use a Peltier cooler instead. So I plugged in the cooler, attached it to a 15 pound dumbell, and used the temperature sensor to see how cold the Peltier could make it. It was pretty handy in that role, as I could monitor the temperature without having to use the USB link... Though my battery pack was less than 5V, which skewed my analog readings, so I wound up plugging it in to USB anyway.
Since I've already hacked up the case of this one a bit I'm planning to add a pushbutton or two - given the space constraints they'll probably have to be tact. switches glued into holes in the case, so the board's gonna be shackled to the casing. But I think a pushbutton will be a very handy addition for switching display modes, etc.
Miscellaneous impressions so far:
- Very neat little product. I've gone and cut it up a bit to add things to it, which also feels like a bit of a shame because it's made the thing less elegant.
- Library documentation seems a bit worthless. Or nonexistant.
- The USB adapter is handy for plugging into my laptop - but it sucks for my desktop. All the accessible USB ports I have face the wrong way. Gotta have that USB A-to-A extension. It makes me wonder if a regular B-type receptacle would have been a better choice after all.